WorldWideScience

Sample records for biodegradable polymer particles

  1. Biodegradable Polymers

    OpenAIRE

    Vroman, Isabelle; Tighzert, Lan

    2009-01-01

    Biodegradable materials are used in packaging, agriculture, medicine and other areas. In recent years there has been an increase in interest in biodegradable polymers. Two classes of biodegradable polymers can be distinguished: synthetic or natural polymers. There are polymers produced from feedstocks derived either from petroleum resources (non renewable resources) or from biological resources (renewable resources). In general natural polymers offer fewer advantages than synthetic polymers. ...

  2. Tuning particle biodegradation through polymer-peptide blend composition.

    Science.gov (United States)

    Gunawan, Sylvia T; Kempe, Kristian; Such, Georgina K; Cui, Jiwei; Liang, Kang; Richardson, Joseph J; Johnston, Angus P R; Caruso, Frank

    2014-12-08

    We report the preparation of polymer-peptide blend replica particles via the mesoporous silica (MS) templated assembly of poly(ethylene glycol)-block-poly(2-diisopropylaminoethyl methacrylate-co-2-(2-(2-(prop-2-ynyloxy)ethoxy)ethoxy)ethyl methacrylate) (PEG45-b-P(DPA55-co-PgTEGMA4)) and poly(l-histidine) (PHis). PEG45-b-P(DPA55-co-PgTEGMA4) was synthesized by atom transfer radical polymerization (ATRP), and was coinfiltrated with PHis into poly(methacrylic acid) (PMA)-coated MS particles assembled from different peptide-to-polymer ratios (1:1, 1:5, 1:10, or 1:15). Subsequent removal of the sacrificial templates and PMA resulted in monodisperse, colloidally stable, noncovalently cross-linked polymer-peptide blend replica particles that were stabilized by a combination of hydrophobic interactions between the PDPA and the PHis, hydrogen bonding between the PEG and PHis backbone, and π-π stacking of the imidazole rings of PHis side chains at physiological pH (pH ∼ 7.4). The synergistic charge-switchable properties of PDPA and PHis, and the enzymatic degradability of PHis, make these particles responsive to pH and enzymes. In vitro studies, in simulated endosomal conditions and inside cells, demonstrated that particle degradation kinetics could be engineered (from 2 to 8 h inside dendritic cells) based on simple adjustment of the peptide-to-polymer ratio used.

  3. Core–shell composite particles composed of biodegradable polymer particles and magnetic iron oxide nanoparticles for targeted drug delivery

    Energy Technology Data Exchange (ETDEWEB)

    Oka, Chiemi; Ushimaru, Kazunori [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan); Horiishi, Nanao [Bengala Techno Laboratory, 9-5-1006, 1-1 Kodai, Miyamae-ku, Kawasaki 216-0007 (Japan); Tsuge, Takeharu [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan); Kitamoto, Yoshitaka, E-mail: kitamoto.y.aa@m.titech.ac.jp [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan)

    2015-05-01

    Core–shell composite particles with biodegradability and superparamagnetic behavior were prepared using a Pickering emulsion for targeted drug delivery based on magnetic guidance. The composite particles were composed of a core of biodegradable polymer and a shell of assembled magnetic iron oxide nanoparticles. It was found that the dispersibility of the nanoparticles is crucial for controlling the core–shell structure. The addition of a small amount of dispersant into the nanoparticle's suspension could improve the dispersibility and led to the formation of composite particles with a thin magnetic shell covering a polymeric core. The composite particles were also fabricated with a model drug loaded into the core, which was released via hydrolysis of the core under strong alkaline conditions. Because the core can also be biodegraded by lipase, this result suggests that the slow release of the drug from the composite particles should occur inside the body. - Highlights: • Core−shell composites with biodegradability and magnetism are prepared. • O/W emulsion stabilized by iron oxide nanoparticles is utilized for the preparation. • The nanoparticle's dispersibility is crucial for controlling the composite structure. • Composites loading a model drug are also prepared. • The model drug is released with decomposition of the composites.

  4. Core–shell composite particles composed of biodegradable polymer particles and magnetic iron oxide nanoparticles for targeted drug delivery

    International Nuclear Information System (INIS)

    Oka, Chiemi; Ushimaru, Kazunori; Horiishi, Nanao; Tsuge, Takeharu; Kitamoto, Yoshitaka

    2015-01-01

    Core–shell composite particles with biodegradability and superparamagnetic behavior were prepared using a Pickering emulsion for targeted drug delivery based on magnetic guidance. The composite particles were composed of a core of biodegradable polymer and a shell of assembled magnetic iron oxide nanoparticles. It was found that the dispersibility of the nanoparticles is crucial for controlling the core–shell structure. The addition of a small amount of dispersant into the nanoparticle's suspension could improve the dispersibility and led to the formation of composite particles with a thin magnetic shell covering a polymeric core. The composite particles were also fabricated with a model drug loaded into the core, which was released via hydrolysis of the core under strong alkaline conditions. Because the core can also be biodegraded by lipase, this result suggests that the slow release of the drug from the composite particles should occur inside the body. - Highlights: • Core−shell composites with biodegradability and magnetism are prepared. • O/W emulsion stabilized by iron oxide nanoparticles is utilized for the preparation. • The nanoparticle's dispersibility is crucial for controlling the composite structure. • Composites loading a model drug are also prepared. • The model drug is released with decomposition of the composites

  5. Absorbable and biodegradable polymers

    CERN Document Server

    Shalaby, Shalaby W

    2003-01-01

    INTRODUCTION NOTES: Absorbable/Biodegradable Polymers: Technology Evolution. DEVELOPMENT AND APPLICATIONOF NEW SYSTEMS: Segmented Copolyesters with Prolonged Strength Retention Profiles. Polyaxial Crystalline Fiber-Forming Copolyester. Polyethylene Glycol-Based Copolyesters. Cyanoacrylate-Based Systems as Tissue Adhesives. Chitosan-Based Systems. Hyaluronic Acid-Based Systems. DEVELOPMENTS IN PREPARATIVE, PROCESSING, AND EVALUATION METHODS: New Approaches to the Synthesis of Crystalline. Fiber-Forming Aliphatic Copolyesters. Advances in Morphological Development to Tailor the Performance of Me

  6. Non-biodegradable polymer particles for drug delivery: A new technology for "bio-active" restorative materials.

    Science.gov (United States)

    Imazato, Satoshi; Kitagawa, Haruaki; Tsuboi, Ririko; Kitagawa, Ranna; Thongthai, Pasiree; Sasaki, Jun-Ichi

    2017-09-26

    To develop dental restorative materials with "bio-active" functions, addition of the capability to release active agents is an effective approach. However, such functionality needs to be attained without compromising the basic properties of the restorative materials. We have developed novel non-biodegradable polymer particles for drug delivery, aimed for application in dental resins. The particles are made using 2-hydroxyethyl methacrylate (HEMA) and a cross-linking monomer trimethylolpropane trimethacrylate (TMPT), with a hydrophilic nature to adsorb proteins or water-soluble antimicrobials. The polyHEMA/TMPT particles work as a reservoir to release fibroblast growth factor-2 (FGF-2) or cetylpyridinium chloride (CPC) in an effective manner. Application of the polyHEMA/TMPT particles loaded with FGF-2 to adhesives, or those loaded with CPC to resin-based endodontic sealers or denture bases/crowns is a promising approach to increase the success of the treatments by conferring "bio-active" properties to these materials to induce tissue regeneration or to inhibit bacterial infection.

  7. Biobased and biodegradable polymer nanocomposites

    Science.gov (United States)

    Qiu, Kaiyan

    In this dissertation, various noncrosslinked and crosslinked biobased and biodegradable polymer nanocomposites were fabricated and characterized. The properties of these polymer nanocomposites, and their relating mechanisms and corresponding applications were studied and discussed in depth. Chapter 1 introduces the research background and objectives of the current research. Chapter 2 presents the development of a novel low cost carbon source for bacterial cellulose (BC) production and fabrication and characterization of biobased polymer nanocomposites using produced BC and soy protein based resins. The carbon source, soy flour extract (SFE), was obtained from defatted soy flour (SF) and BC yield achieved using SFE medium was high. The results of this study showed that SFE consists of five sugars and Acetobacter xylinum metabolized sugars in a specific order. Chapter 3 discusses the fabrication and characterization of biodegradable polymer nanocomposites using BC and polyvinyl alcohol (PVA). These polymer nanocomposites had excellent tensile and thermal properties. Crosslinking of PVA using glutaraldehyde (GA) not only increased the mechanical and thermal properties but the water-resistance. Chapter 4 describes the development and characterization of microfibrillated cellulose (MFC) based biodegradable polymer nanocomposites by blending MFC suspension with PVA. Chemical crosslinking of the polymer nanocomposites was carried out using glyoxal to increase the mechanical and thermal properties as well as to make the PVA partially water-insoluble. Chapter 5 reports the development and characterization of halloysite nanotube (HNT) reinforced biodegradable polymer nanocomposites utilizing HNT dispersion and PVA. Several separation techniques were used to obtain individualized HNT dispersion. The results indicated uniform dispersion of HNTs in both PVA and malonic acid (MA) crosslinked PVA resulted in excellent mechanical and thermal properties of the materials, especially

  8. CLASSIFICATION OF BIODEGRADABLE POLYMERS

    Directory of Open Access Journals (Sweden)

    I. I. Karpunin

    2015-01-01

    Full Text Available The executed investigations have made it possible to ascertain that a morphological structure of starch granules mainly determine technological peculiarities of starch isolation from raw material, its modification and its later use. Morphological structure of starch granules primarily depends on type of plant starch-containing raw material which has been used for its isolation. Class of raw material exerts a strong impact on the shape and size of the granules. Linear “light” amylose chains and “heavy” amylopectin branch chains form a starch granule ultrastructure. X-ray research has proved that starch granules are characterized by presence of interlacing amorphous and crystalline regions. In this case polymer orientation using stretching of the obtained end product influences on its physical and mechanical  indices which are increasing due to polymer orientation. For the purpose of packaging orientation of polymer films can solve such important problems as significant improvement of operational properties, creation of  thermosetting film materials, improvement of qualitative indices of the recycled film.Results of the conducted research have proved the fact that it is necessary to make changes in technology in order to increase biological degradability of the recycled packaging made from polymers and improve physical and mechanical indices. In this regard film production technology presupposes usage of such substances as stark and others which are characterized by rather large presence of branch chains of molecules and interlacing amorphous and crystalline regions. Such approach makes it possible to obtain after-use package which is strong and quickly degradable by micro-organisms.

  9. A model for simultaneous crystallisation and biodegradation of biodegradable polymers.

    Science.gov (United States)

    Han, Xiaoxiao; Pan, Jingzhe

    2009-01-01

    This paper completes the model of biodegradation for biodegradable polymers that was previously developed by Wang et al. (Wang Y, Pan J, Han X, Sinka, Ding L. A phenomenological model for the degradation of biodegradable polymers. Biomaterials 2008;29:3393-401). Crystallisation during biodegradation was not considered in the previous work which is the topic of the current paper. For many commonly used biodegradable polymers, there is a strong interplay between crystallisation and hydrolysis reaction during biodegradation - the chain cleavage caused by the hydrolysis reaction provides an extra mobility for the polymer chains to crystallise and the resulting crystalline phase becomes more resistant to further hydrolysis reaction. This paper presents a complete theory to describe this interplay. The fundamental equations in the Avrami's theory for crystallisation are modified and coupled to the diffusion-reaction equations that were developed in our previous work. The mathematical equations are then applied to three biodegradable polymers for which long term degradation data are available in the literature. It is shown that the model can capture the behavior of the major biodegradable polymers very well.

  10. Engineered biosynthesis of biodegradable polymers.

    Science.gov (United States)

    Jambunathan, Pooja; Zhang, Kechun

    2016-08-01

    Advances in science and technology have resulted in the rapid development of biobased plastics and the major drivers for this expansion are rising environmental concerns of plastic pollution and the depletion of fossil-fuels. This paper presents a broad view on the recent developments of three promising biobased plastics, polylactic acid (PLA), polyhydroxyalkanoate (PHA) and polybutylene succinate (PBS), well known for their biodegradability. The article discusses the natural and recombinant host organisms used for fermentative production of monomers, alternative carbon feedstocks that have been used to lower production cost, different metabolic engineering strategies used to improve product titers, various fermentation technologies employed to increase productivities and finally, the different downstream processes used for recovery and purification of the monomers and polymers.

  11. Electrospun biodegradable polymers loaded with bactericide agents

    Directory of Open Access Journals (Sweden)

    Ramaz Katsarava

    2016-03-01

    Full Text Available Development of materials with an antimicrobial activity is fundamental for different sectors, including medicine and health care, water and air treatment, and food packaging. Electrospinning is a versatile and economic technique that allows the incorporation of different natural, industrial, and clinical agents into a wide variety of polymers and blends in the form of micro/nanofibers. Furthermore, the technique is versatile since different constructs (e.g. those derived from single electrospinning, co-electrospinning, coaxial electrospinning, and miniemulsion electrospinning can be obtained to influence the ability to load agents with different characteristics and stability and to modify the release behaviour. Furthermore, antimicrobial agents can be loaded during the electrospinning process or by a subsequent coating process. In order to the mitigate burst release effect, it is possible to encapsulate the selected drug into inorganic nanotubes and nanoparticles, as well as in organic cyclodextrine polysaccharides. In the same way, processes that involve covalent linkage of bactericide agents during surface treatment of electrospun samples may also be considered. The present review is focused on more recent works concerning the electrospinning of antimicrobial polymers. These include chitosan and common biodegradable polymers with activity caused by the specific load of agents such as metal and metal oxide particles, quaternary ammonium compounds, hydantoin compounds, antibiotics, common organic bactericides, and bacteriophages.

  12. Synthetic biodegradable functional polymers for tissue engineering: a brief review

    OpenAIRE

    BaoLin, GUO; MA, Peter X.

    2014-01-01

    Scaffolds play a crucial role in tissue engineering. Biodegradable polymers with great processing flexibility are the predominant scaffolding materials. Synthetic biodegradable polymers with well-defined structure and without immunological concerns associated with naturally derived polymers are widely used in tissue engineering. The synthetic biodegradable polymers that are widely used in tissue engineering, including polyesters, polyanhydrides, polyphosphazenes, polyurethane, and poly (glyce...

  13. Biodegradable polymers derived from amino acids.

    Science.gov (United States)

    Khan, Wahid; Muthupandian, Saravanan; Farah, Shady; Kumar, Neeraj; Domb, Abraham J

    2011-12-08

    In the past three decades, the use of polymeric materials has increased dramatically for biomedical applications. Many α-amino acids derived biodegradable polymers have also been intensely developed with the main goal to obtain bio-mimicking functional biomaterials. Polymers derived from α-amino acids may offer many advantages, as these polymers: (a) can be modified further to introduce new functions such as imaging, molecular targeting and drugs can be conjugated chemically to these polymers, (b) can improve on better biological properties like cell migration, adhesion and biodegradability, (c) can improve on mechanical and thermal properties and (d) their degradation products are expected to be non-toxic and readily metabolized/excreted from the body. This manuscript focuses on biodegradable polymers derived from natural amino acids, their synthesis, biocompatibility and biomedical applications. It is observed that polymers derived from α-amino acids constitute a promising family of biodegradable materials. These provide innovative multifunctional polymers possessing amino acid side groups with biological activity and with innumerous potential applications. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Biodegradation of Moringa oleifera's polymer blends.

    Science.gov (United States)

    Finzi-Quintão, Cristiane Medina; Novack, Kátia Monteiro; Bernardes-Silva, Ana Cláudia; Silva, Thais D; Moreira, Lucas E S; Braga, Luiza E M

    2017-11-10

    Vegetable oils are used as a base for the synthesis of polymers and monomers with structures similar to that of petroleum, as plasticizers for conventional polymers and biodegrading additives. The Moringa oleifera oil was extracted from seeds and polymerized after being submitted to 16 h of microwave irradiation without catalysers. This polymer was characterized and the efficiency of the oil polymerization was verified by the reduction of double bonds and the increase of molecular weight up to 50,000 g mol -1 . Films produced by a mixture of low-density polyethylene (LDPE) with poly(butylene adipate-co-terephthalate)/poly(lactic acid) (PBAT/PLA) present low tensile resistance and low biodegradation behaviour. In order to improve those properties, the Moringa polymer (PMO) was mixed with LDPE and PBAT/PLA in specific mass concentrations. The films produced with this mixture were characterized and submitted to biodegradation analysis. The PMO behaves as a compatibilizer by improving thermal properties, reducing the crystalline phase and improving the biodegradation behaviour. The biodegradation improved up to five times in comparison to conventional polymers and it restores the mechanical properties.

  15. Biodegradable Polymers and Stem Cells for Bioprinting

    Directory of Open Access Journals (Sweden)

    Meijuan Lei

    2016-04-01

    Full Text Available It is imperative to develop organ manufacturing technologies based on the high organ failure mortality and serious donor shortage problems. As an emerging and promising technology, bioprinting has attracted more and more attention with its super precision, easy reproduction, fast manipulation and advantages in many hot research areas, such as tissue engineering, organ manufacturing, and drug screening. Basically, bioprinting technology consists of inkjet bioprinting, laser-based bioprinting and extrusion-based bioprinting techniques. Biodegradable polymers and stem cells are common printing inks. In the printed constructs, biodegradable polymers are usually used as support scaffolds, while stem cells can be engaged to differentiate into different cell/tissue types. The integration of biodegradable polymers and stem cells with the bioprinting techniques has provided huge opportunities for modern science and technologies, including tissue repair, organ transplantation and energy metabolism.

  16. Biodegradable Polymers and Stem Cells for Bioprinting.

    Science.gov (United States)

    Lei, Meijuan; Wang, Xiaohong

    2016-04-29

    It is imperative to develop organ manufacturing technologies based on the high organ failure mortality and serious donor shortage problems. As an emerging and promising technology, bioprinting has attracted more and more attention with its super precision, easy reproduction, fast manipulation and advantages in many hot research areas, such as tissue engineering, organ manufacturing, and drug screening. Basically, bioprinting technology consists of inkjet bioprinting, laser-based bioprinting and extrusion-based bioprinting techniques. Biodegradable polymers and stem cells are common printing inks. In the printed constructs, biodegradable polymers are usually used as support scaffolds, while stem cells can be engaged to differentiate into different cell/tissue types. The integration of biodegradable polymers and stem cells with the bioprinting techniques has provided huge opportunities for modern science and technologies, including tissue repair, organ transplantation and energy metabolism.

  17. Biodegradable Shape Memory Polymers in Medicine.

    Science.gov (United States)

    Peterson, Gregory I; Dobrynin, Andrey V; Becker, Matthew L

    2017-11-01

    Shape memory materials have emerged as an important class of materials in medicine due to their ability to change shape in response to a specific stimulus, enabling the simplification of medical procedures, use of minimally invasive techniques, and access to new treatment modalities. Shape memory polymers, in particular, are well suited for such applications given their excellent shape memory performance, tunable materials properties, minimal toxicity, and potential for biodegradation and resorption. This review provides an overview of biodegradable shape memory polymers that have been used in medical applications. The majority of biodegradable shape memory polymers are based on thermally responsive polyesters or polymers that contain hydrolyzable ester linkages. These materials have been targeted for use in applications pertaining to embolization, drug delivery, stents, tissue engineering, and wound closure. The development of biodegradable shape memory polymers with unique properties or responsiveness to novel stimuli has the potential to facilitate the optimization and development of new medical applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Biodegradable Poly(polyol sebacate) Polymers

    OpenAIRE

    Bruggeman, Joost P.; de Bruin, Berend-Jan; Bettinger, Christopher J.; Langer, Robert

    2008-01-01

    We have developed a family of synthetic biodegradable polymers that are composed of structural units endogenous to the human metabolism, designated poly(polyol sebacates) (PPS) polymers. Material properties of PPS polymers can be tuned by altering the polyol monomer and reacting stiochiometric ratio of sebacic acid. These thermoset networks exhibited tensile Young’s moduli ranging from 0.37 ± 0.08 to 378 ± 33 MPa with maximum elongations at break from 10.90 ± 1.37 to 205.16 ± 55.76%, and glas...

  19. Nanocomposites with biodegradable polymers synthesis properties and future perspectives

    CERN Document Server

    2011-01-01

    Polymers are used in practically every facet of daily life. Most polymers come from fossil fuels and are not biodegradable, causing long-term environmental hazards. Biodegradable polymers provide an alternative class of materials. Composites of such polymers have high potential within a wide spectrum of applications.

  20. Biodegradable Poly(polyol sebacate) Polymers

    Science.gov (United States)

    Bruggeman, Joost P.; de Bruin, Berend-Jan; Bettinger, Christopher J.; Langer, Robert

    2010-01-01

    We have developed a family of synthetic biodegradable polymers that are composed of structural units endogenous to the human metabolism, designated poly(polyol sebacates) (PPS) polymers. Material properties of PPS polymers can be tuned by altering the polyol monomer and reacting stiochiometric ratio of sebacic acid. These thermoset networks exhibited tensile Young’s moduli ranging from 0.37 ± 0.08 to 378 ± 33 MPa with maximum elongations at break from 10.90 ± 1.37 to 205.16 ± 55.76%, and glass-transition temperatures ranged from ~7 to 46 °C. In vitro degradation under physiological conditions was slower than in vivo degradation rates observed for some PPS polymers. PPS polymers demonstrated similar in vitro and in vivo biocompatibility compared to poly(L-lactic-co-glycolic acid) (PLGA). PMID:18824260

  1. Biodegradable polymers in Quebec; Les polymeres biodegradables au Quebec

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    Poly-hydroxy-alkanoates (PHA) are natural polymers made from renewable resources and are easily recyclable, hydrolyzable and biodegradable. Thanks to genetic technologies, PHA can be synthesized from plants or bacteria and can be used in various domains ranging from the manufacturing of packing materials to medical applications. Moreover, their properties make them good substitutes of equivalent petroleum-derived compounds. This report makes a status of Quebec's research work on PHAs and presents the three main research centers in which such studies are carried out: the biotechnology research institute, the Mc Gill university and the Polytechnique school of Montreal. (J.S.)

  2. Control of colloidal CaCO3 suspension by using biodegradable polymers during fabrication

    Directory of Open Access Journals (Sweden)

    Nemany Abdelhamid Nemany Hanafy

    2015-03-01

    The aim of this work was to investigate the synthesis process of CaCO3 particles in different experimental conditions: calcium carbonate was produced in presence and in absence of water and with addition of appropriate polymers. In particular, chitosan (CHI and poly acrylic acid (PAA were chosen as biodegradable polymers whereas PSS and PAH were chosen as non-biodegradable polymers. Shape and diameter of particles were investigated by using transmission and scanning electron microscopy, elemental composition was inferred by energy dispersive X-ray analyses whereas their charges were explored by using zeta potential.

  3. Development of aliphatic biodegradable photoluminescent polymers.

    Science.gov (United States)

    Yang, Jian; Zhang, Yi; Gautam, Santosh; Liu, Li; Dey, Jagannath; Chen, Wei; Mason, Ralph P; Serrano, Carlos A; Schug, Kevin A; Tang, Liping

    2009-06-23

    None of the current biodegradable polymers can function as both implant materials and fluorescent imaging probes. The objective of this study was to develop aliphatic biodegradable photoluminescent polymers (BPLPs) and their associated cross-linked variants (CBPLPs) for biomedical applications. BPLPs are degradable oligomers synthesized from biocompatible monomers including citric acid, aliphatic diols, and various amino acids via a convenient and cost-effective polycondensation reaction. BPLPs can be further cross-linked into elastomeric cross-linked polymers, CBPLPs. We have shown representatively that BPLP-cysteine (BPLP-Cys) and BPLP-serine (BPLP-Ser) offer advantages over the traditional fluorescent organic dyes and quantum dots because of their preliminarily demonstrated cytocompatibility in vitro, minimal chronic inflammatory responses in vivo, controlled degradability and high quantum yields (up to 62.33%), tunable fluorescence emission (up to 725 nm), and photostability. The tensile strength of CBPLP-Cys film ranged from 3.25 +/- 0.13 MPa to 6.5 +/- 0.8 MPa and the initial Modulus was in a range of 3.34 +/- 0.15 MPa to 7.02 +/- 1.40 MPa. Elastic CBPLP-Cys could be elongated up to 240 +/- 36%. The compressive modulus of BPLP-Cys (0.6) (1:1:0.6 OD:CA:Cys) porous scaffold was 39.60 +/- 5.90 KPa confirming the soft nature of the scaffolds. BPLPs also possess great processability for micro/nano-fabrication. We demonstrate the feasibility of using BPLP-Ser nanoparticles ("biodegradable quantum dots") for in vitro cellular labeling and noninvasive in vivo imaging of tissue engineering scaffolds. The development of BPLPs and CBPLPs represents a new direction in developing fluorescent biomaterials and could impact tissue engineering, drug delivery, bioimaging.

  4. Biodegradable Polymers in Bone Tissue Engineering

    Directory of Open Access Journals (Sweden)

    Leon E. Govaert

    2009-07-01

    Full Text Available The use ofdegradable polymers in medicine largely started around the mid 20th century with their initial use as in vivo resorbing sutures. Thorough knowledge on this topic as been gained since then and the potential applications for these polymers were, and still are, rapidly expanding. After improving the properties of lactic acid-based polymers, these were no longer studied only from a scientific point of view, but also for their use in bone surgery in the 1990s. Unfortunately, after implanting these polymers, different foreign body reactions ranging from the presence of white blood cells to sterile sinuses with resorption of the original tissue were observed. This led to the misconception that degradable polymers would, in all cases, lead to inflammation and/or osteolysis at the implantation site. Nowadays, we have accumulated substantial knowledge on the issue of biocompatibility of biodegradable polymers and are able to tailor these polymers for specific applications and thereby strongly reduce the occurrence of adverse tissue reactions. However, the major issue of biofunctionality, when mechanical adaptation is taken into account, has hitherto been largely unrecognized. A thorough understanding of how to improve the biofunctionality, comprising biomechanical stability, but also visualization and sterilization of the material, together with the avoidance of fibrotic tissue formation and foreign body reactions, may greatly enhance the applicability and safety of degradable polymers in a wide area of tissue engineering applications. This review will address our current understanding of these biofunctionality factors, and will subsequently discuss the pitfalls remaining and potential solutions to solve these problems.

  5. Synthetic biodegradable functional polymers for tissue engineering: a brief review.

    Science.gov (United States)

    BaoLin, Guo; Ma, Peter X

    2014-04-01

    Scaffolds play a crucial role in tissue engineering. Biodegradable polymers with great processing flexibility are the predominant scaffolding materials. Synthetic biodegradable polymers with well-defined structure and without immunological concerns associated with naturally derived polymers are widely used in tissue engineering. The synthetic biodegradable polymers that are widely used in tissue engineering, including polyesters, polyanhydrides, polyphosphazenes, polyurethane, and poly (glycerol sebacate) are summarized in this article. New developments in conducting polymers, photoresponsive polymers, amino-acid-based polymers, enzymatically degradable polymers, and peptide-activated polymers are also discussed. In addition to chemical functionalization, the scaffold designs that mimic the nano and micro features of the extracellular matrix (ECM) are presented as well, and composite and nanocomposite scaffolds are also reviewed.

  6. Critical evaluation of biodegradable polymers used in nanodrugs

    Science.gov (United States)

    Marin, Edgar; Briceño, Maria Isabel; Caballero-George, Catherina

    2013-01-01

    Use of biodegradable polymers for biomedical applications has increased in recent decades due to their biocompatibility, biodegradability, flexibility, and minimal side effects. Applications of these materials include creation of skin, blood vessels, cartilage scaffolds, and nanosystems for drug delivery. These biodegradable polymeric nanoparticles enhance properties such as bioavailability and stability, and provide controlled release of bioactive compounds. This review evaluates the classification, synthesis, degradation mechanisms, and biological applications of the biodegradable polymers currently being studied as drug delivery carriers. In addition, the use of nanosystems to solve current drug delivery problems are reviewed. PMID:23990720

  7. Critical evaluation of biodegradable polymers used in nanodrugs.

    Science.gov (United States)

    Marin, Edgar; Briceño, Maria Isabel; Caballero-George, Catherina

    2013-01-01

    Use of biodegradable polymers for biomedical applications has increased in recent decades due to their biocompatibility, biodegradability, flexibility, and minimal side effects. Applications of these materials include creation of skin, blood vessels, cartilage scaffolds, and nanosystems for drug delivery. These biodegradable polymeric nanoparticles enhance properties such as bioavailability and stability, and provide controlled release of bioactive compounds. This review evaluates the classification, synthesis, degradation mechanisms, and biological applications of the biodegradable polymers currently being studied as drug delivery carriers. In addition, the use of nanosystems to solve current drug delivery problems are reviewed.

  8. Partial Discharge Degradation of Several Biodegradable Polymers

    Science.gov (United States)

    Fuse, Norikazu; Fujita, Shinjiro; Hirai, Naoshi; Tanaka, Toshikatsu; Kozako, Masahiro; Kohtoh, Masanori; Okabe, Shigemitsu; Ohki, Yoshimichi

    Partial discharge (PD) resistance was examined by applying a constant voltage for four kinds of biodegradable polymers, i.e. poly-L-lactic acid (PLLA), polyethylene terephthalate succinate (PETS), poly ε-caprolactone butylene succinate (PCL-BS), and polybutylene succinate (PBS), and the results were compared with those of low density polyethylene (LDPE) and crosslinked low density polyethylene (XLPE). The PD resistance is determined by the erosion depth and the surface roughness caused by PDs, and is ranked as LDPE ≅ XLPE > PLLA ≅ PETS > PBS > PCL-BS. This means that the sample with a lower permittivity has better PD resistance. Furthermore, observations of the sample surface by a polarization microscope and a laser confocal one reveal that crystalline regions with spherulites are more resistant to PDs than amorphous regions. Therefore, good PD resistance can be achieved by the sample with a high crystallinity and a low permittivity.

  9. Biodegradable and biocompatible polymers for tissue engineering application: a review.

    Science.gov (United States)

    Asghari, Fatemeh; Samiei, Mohammad; Adibkia, Khosro; Akbarzadeh, Abolfazl; Davaran, Soodabeh

    2017-03-01

    Since so many years ago, tissue damages that are caused owing to various reasons attract scientists' attention to find a practical way to treat. In this regard, many studies were conducted. Nano scientists also suggested some ways and the newest one is called tissue engineering. They use biodegradable polymers in order to replace damaged structures in tissues to make it practical. Biodegradable polymers are dominant scaffolding materials in tissue engineering field. In this review, we explained about biodegradable polymers and their application as scaffolds.

  10. Methods for Evaluating the Biodegradability of Environmentally Degradable Polymers

    NARCIS (Netherlands)

    Zee, van der M.

    2014-01-01

    This chapter presents an overview of the current knowledge on experimental methods for monitoring the biodegradability of polymeric materials. The focus is, in particular, on the biodegradation of materials under environmental conditions. Examples of in vivo degradation of polymers used in

  11. Toward biodegradable nanogel star polymers via organocatalytic ROP.

    Science.gov (United States)

    Appel, Eric A; Lee, Victor Y; Nguyen, Timothy T; McNeil, Melanie; Nederberg, Frederik; Hedrick, James L; Swope, William C; Rice, Jullia E; Miller, Robert D; Sly, Joseph

    2012-06-21

    Organocatalytic ring opening polymerization (OROP) is used to effect the rapid, scalable, room temperature formation of size-controlled, highly uniform, polyvalent, nanogel star polymer nanoparticles of biodegradable composition.

  12. Polymer nanocomposites: polymer and particle dynamics

    KAUST Repository

    Kim, Daniel

    2012-01-01

    Polymer nanocomposites containing nanoparticles smaller than the random coil size of their host polymer chains are known to exhibit unique properties, such as lower viscosity and glass transition temperature relative to the neat polymer melt. It has been hypothesized that these unusual properties result from fast diffusion of the nanostructures in the host polymer, which facilitates polymer chain relaxation by constraint release and other processes. In this study, the effects of addition of sterically stabilized inorganic nanoparticles to entangled cis-1,4-polyisoprene and polydimethylsiloxane on the overall rheology of nanocomposites are discussed. In addition, insights about the relaxation of the host polymer chains and transport properties of nanoparticles in entangled polymer nanocomposites are presented. The nanoparticles are found to act as effective plasticizers for their entangled linear hosts, and below a critical, chemistry and molecular-weight dependent particle volume fraction, lead to reduced viscosity, glass transition temperature, number of entanglements, and polymer relaxation time. We also find that the particle motions in the polymer host are hyperdiffusive and at the nanoparticle length scale, the polymer host acts like a simple, ideal fluid and the composites\\' viscosity rises with increasing particle concentration. © 2012 The Royal Society of Chemistry.

  13. Computational analysis for biodegradation of exogenously depolymerizable polymer

    Science.gov (United States)

    Watanabe, M.; Kawai, F.

    2018-03-01

    This study shows that microbial growth and decay in a biodegradation process of exogenously depolymerizable polymer are controlled by consumption of monomer units. Experimental outcomes for residual polymer were incorporated in inverse analysis for a degradation rate. The Gauss-Newton method was applied to an inverse problem for two parameter values associated with the microbial population. A biodegradation process of polyethylene glycol was analyzed numerically, and numerical outcomes were obtained.

  14. DNA polyplexes formed using PEGylated biodegradable hyperbranched polymers.

    Science.gov (United States)

    Tao, Lei; Chou, William C; Tan, Beng H; Davis, Thomas P

    2010-06-11

    A novel PEGylated biodegradable hyperbranched PEG-b-PDMAEMA has been synthesized. The low toxicity, small molecular weight PDMAEMA chains were crosslinked using a biodegradable disulfide-based dimethacrylate (DSDMA) agent to yield higher molecular weight hyperbranched polymers. PEG chains were linked onto the polymer surface, masking the positive charge (as shown by Zeta potential measurements) and reducing the toxicity of the polymer. The hyperbranched structures were also cleaved under reducing conditions and analyzed, confirming the expected component structures. The hyperbranched polymer was mixed with DNA and efficient binding was shown to occur through electrostatic interactions. The hyperbranched structures could be reduced easily, generating lower toxicity oligomer chains.

  15. Biodegradable polymers for targeted delivery of anti-cancer drugs.

    Science.gov (United States)

    Doppalapudi, Sindhu; Jain, Anjali; Domb, Abraham J; Khan, Wahid

    2016-06-01

    Biodegradable polymers have been used for more than three decades in cancer treatment and have received increased interest in recent years. A range of biodegradable polymeric drug delivery systems designed for localized and systemic administration of therapeutic agents as well as tumor-targeting macromolecules has entered into the clinical phase of development, indicating the significance of biodegradable polymers in cancer therapy. This review elaborates upon applications of biodegradable polymers in the delivery and targeting of anti-cancer agents. Design of various drug delivery systems based on biodegradable polymers has been described. Moreover, the indication of polymers in the targeted delivery of chemotherapeutic drugs via passive, active targeting, and localized drug delivery are also covered. Biodegradable polymer-based drug delivery systems have the potential to deliver the payload to the target and can enhance drug availability at desired sites. Systemic toxicity and serious side effects observed with conventional cancer therapeutics can be significantly reduced with targeted polymeric systems. Still, there are many challenges that need to be met with respect to the degradation kinetics of the system, diffusion of drug payload within solid tumors, targeting tumoral tissue and tumor heterogeneity.

  16. An entropy spring model for the Young's modulus change of biodegradable polymers during biodegradation.

    Science.gov (United States)

    Wang, Ying; Han, Xiaoxiao; Pan, Jingzhe; Sinka, Csaba

    2010-01-01

    This paper presents a model for the change in Young's modulus of biodegradable polymers due to hydrolysis cleavage of the polymer chains. The model is based on the entropy spring theory for amorphous polymers. It is assumed that isolated polymer chain cleavage and very short polymer chains do not affect the entropy change in a linear biodegradable polymer during its deformation. It is then possible to relate the Young's modulus to the average molecular weight in a computer simulated hydrolysis process of polymer chain sessions. The experimental data obtained by Tsuji [Tsuji, H., 2002. Autocatalytic hydrolysis of amorphous-made polylactides: Effects of L-lactide content, tacticity, and enantiomeric polymer blending. Polymers 43, 1789-1796] for poly(L-lactic acid) and poly(D-lactic acid) are examined using the model. It is shown that the model can provide a common thread through Tsuji's experimental data. A further numerical case study demonstrates that the Young's modulus obtained using very thin samples, such as those obtained by Tsuji, cannot be directly used to calculate the load carried by a device made of the same polymer but of various thicknesses. This is because the Young's modulus varies significantly in a biodegradable device due to the heterogeneous nature of the hydrolysis reaction. The governing equations for biodegradation and the relation between the Young's modulus and average molecular weight can be combined to calculate the load transfer from a degrading device to a healing bone.

  17. Solvent-free formation of hydroxyapatite coated biodegradable particles via nanoparticle-stabilized emulsion route

    Energy Technology Data Exchange (ETDEWEB)

    Okada, Masahiro, E-mail: okada-m@cc.osaka-dent.ac.jp [Department of Biomaterials, Osaka Dental University, 8-1 Kuzuha-Hanazono, Hirakata, Osaka 573-1121 (Japan); Fujii, Syuji, E-mail: s.fujii@chem.oit.ac.jp [Department of Applied Chemistry, Osaka Institute of Technology 5-16-1 Ohmiya, Asahi, Osaka 535-8585 (Japan); Nishimura, Taiki; Nakamura, Yoshinobu [Department of Applied Chemistry, Osaka Institute of Technology 5-16-1 Ohmiya, Asahi, Osaka 535-8585 (Japan); Takeda, Shoji [Department of Biomaterials, Osaka Dental University, 8-1 Kuzuha-Hanazono, Hirakata, Osaka 573-1121 (Japan); Furuzono, Tsutomu [Department of Biomedical Engineering, School of Biology-Oriented Science and Technology, Kinki University, 930 Nishi-Mitani, Kinokawa, Wakayama 649-6493 (Japan)

    2012-12-01

    Highlights: Black-Right-Pointing-Pointer Hydroxyapatite (HAp) nanoparticles stabilized polymer melt-in-water emulsions without any molecular surfactants. Black-Right-Pointing-Pointer Interaction between polymer and HAp played a crucial role. Black-Right-Pointing-Pointer HAp-coated polymer particles were obtained from the emulsions without any organic solvents. - Abstract: Hydroxyapatite (HAp) nanoparticle-coated biodegradable polymer particles were fabricated from a nanoparticle-stabilized emulsion in the absence of any molecular surfactants or organic solvents. First, a polymer melt-in-water emulsion was prepared by mixing a water phase containing nanosized HAp particles as a particulate emulsifier and an oil phase consisting of poly({epsilon}-caprolactone) (PCL) or poly(L-lactide-co-{epsilon}-caprolactone) (P(LLA-CL)) above its melting point. It was clarified that the interaction between ester/carboxyl groups of the polymers and the HAp nanoparticles at the polymer-water interface played a crucial role to prepare the nanoparticle-stabilized emulsion. The HAp nanoparticle-coated biodegradable polymer particle (a polymer solid-in-water emulsion) was fabricated by cooling the emulsion. The particle morphology and particle size were evaluated using scanning electron microscope.

  18. Polyethylene Modification as Biodegradable Composite Polymer for Packing Materials

    International Nuclear Information System (INIS)

    Deswita; Aloma KK; Sudirman; Indra Gunawan

    2008-01-01

    The synthesis of biodegradable polymer using blending method has been done. The aim of this research is to synthesize kinds of biodegradable composite polymer materials which could be applied in many kinds of requirements such as environmental friendly packaging and degradable. In this paper, the synthetic of biodegradable composite polymer was performed by adding biodegradable filler to the synthetic polymer using blending method. In this experiment Low Linier Density Polyethylene (LLDPE), High Density Polyethylene (HDPE) and filler of tapioca were used. The variation of tapioca meal composition were 50 in weight percent, 55 in weight percent, 60 in weight percent, 65 in weight percent, 70 in weight percent and 75 in weight percent. The characterization was done by means of thermal test, microstructure test, biodegradable and mechanical test. The result showed that the mechanical properties of the materials decreased with increasing composition of tapioca but did not show significant change to the polymer composite materials. For burrying time inside the ground of 8 weeks, all specimens based on polymer LLDPE for all composition of tapioca filler were degraded inside the ground, where as for all specimens based on polymer HDPE with all composition of tapioca filler did not show any degradation. (author)

  19. Acceleration of biodegradation by ultraviolet femtosecond laser irradiation to biodegradable polymer

    Science.gov (United States)

    Shibata, Akimichi; Yada, Shuhei; Kondo, Naonari; Terakawa, Mitsuhiro

    2017-02-01

    Biodegradability is a key property of biodegradable polymers for tissue scaffold applications. Among the methods to control biodegradability, laser processing is a simple technique, which enables the alteration of biodegradability even after molding. Since ultrafast laser processing realizes precise processing of biodegradable polymer with less heat affected zone, ultrafast laser processing has the potential to fabricate tissue scaffolds and to control its biodegradability. In this study, we investigate the effect of femtosecond laser wavelength on the biodegradability of PLGA. We evaluated the biodegradability of PLGA irradiated with femtosecond laser pulses at the wavelength of 800, 400, 266 nm by the measurement of the change in mass of PLGA during water immersion. The results of degradation tests indicate that PLGA irradiated with the shorter wavelength show faster water absorption as well as rapid mass decrease. Since the results of X-ray photoelectron spectroscopy analysis indicate that the chemical bonds of PLGA irradiated with the shorter wavelength are dissociated more significantly, the acceleration of the biodegradation could be attributable to the decrease in molecular weight by chemical bond breaking.

  20. Solvent-free formation of hydroxyapatite coated biodegradable particles via nanoparticle-stabilized emulsion route

    International Nuclear Information System (INIS)

    Okada, Masahiro; Fujii, Syuji; Nishimura, Taiki; Nakamura, Yoshinobu; Takeda, Shoji; Furuzono, Tsutomu

    2012-01-01

    Highlights: ► Hydroxyapatite (HAp) nanoparticles stabilized polymer melt-in-water emulsions without any molecular surfactants. ► Interaction between polymer and HAp played a crucial role. ► HAp-coated polymer particles were obtained from the emulsions without any organic solvents. - Abstract: Hydroxyapatite (HAp) nanoparticle-coated biodegradable polymer particles were fabricated from a nanoparticle-stabilized emulsion in the absence of any molecular surfactants or organic solvents. First, a polymer melt-in-water emulsion was prepared by mixing a water phase containing nanosized HAp particles as a particulate emulsifier and an oil phase consisting of poly(ε-caprolactone) (PCL) or poly(L-lactide-co-ε-caprolactone) (P(LLA-CL)) above its melting point. It was clarified that the interaction between ester/carboxyl groups of the polymers and the HAp nanoparticles at the polymer–water interface played a crucial role to prepare the nanoparticle-stabilized emulsion. The HAp nanoparticle-coated biodegradable polymer particle (a polymer solid-in-water emulsion) was fabricated by cooling the emulsion. The particle morphology and particle size were evaluated using scanning electron microscope.

  1. Imaging the intracellular degradation of biodegradable polymer nanoparticles

    Directory of Open Access Journals (Sweden)

    Anne-Kathrin Barthel

    2014-10-01

    Full Text Available In recent years, the development of smart drug delivery systems based on biodegradable polymeric nanoparticles has become of great interest. Drug-loaded nanoparticles can be introduced into the cell interior via endocytotic processes followed by the slow release of the drug due to degradation of the nanoparticle. In this work, poly(L-lactic acid (PLLA was chosen as the biodegradable polymer. Although common degradation of PLLA has been studied in various biological environments, intracellular degradation processes have been examined only to a very limited extent. PLLA nanoparticles with an average diameter of approximately 120 nm were decorated with magnetite nanocrystals and introduced into mesenchymal stem cells (MSCs. The release of the magnetite particles from the surface of the PLLA nanoparticles during the intracellular residence was monitored by transmission electron microscopy (TEM over a period of 14 days. It was demonstrated by the release of the magnetite nanocrystals from the PLLA surface that the PLLA nanoparticles do in fact undergo degradation within the cell. Furthermore, even after 14 days of residence, the PLLA nanoparticles were found in the MSCs. Additionally, the ultrastructural TEM examinations yield insight into the long term intercellular fate of these nanoparticles. From the statistical analysis of ultrastructural details (e.g., number of detached magnetite crystals, and the number of nanoparticles in one endosome, we demonstrate the importance of TEM studies for such applications in addition to fluorescence studies (flow cytometry and confocal laser scanning microscopy.

  2. Bio-degradable highly fluorescent conjugated polymer nanoparticles for bio-medical imaging applications.

    Science.gov (United States)

    Repenko, Tatjana; Rix, Anne; Ludwanowski, Simon; Go, Dennis; Kiessling, Fabian; Lederle, Wiltrud; Kuehne, Alexander J C

    2017-09-07

    Conjugated polymer nanoparticles exhibit strong fluorescence and have been applied for biological fluorescence imaging in cell culture and in small animals. However, conjugated polymer particles are hydrophobic and often chemically inert materials with diameters ranging from below 50 nm to several microns. As such, conjugated polymer nanoparticles cannot be excreted through the renal system. This drawback has prevented their application for clinical bio-medical imaging. Here, we present fully conjugated polymer nanoparticles based on imidazole units. These nanoparticles can be bio-degraded by activated macrophages. Reactive oxygen species induce scission of the conjugated polymer backbone at the imidazole unit, leading to complete decomposition of the particles into soluble low molecular weight fragments. Furthermore, the nanoparticles can be surface functionalized for directed targeting. The approach opens a wide range of opportunities for conjugated polymer particles in the fields of medical imaging, drug-delivery, and theranostics.Conjugated polymer nanoparticles have been applied for biological fluorescence imaging in cell culture and in small animals, but cannot readily be excreted through the renal system. Here the authors show fully conjugated polymer nanoparticles based on imidazole units that can be bio-degraded by activated macrophages.

  3. Biodegradable polymers for electrospinning: towards biomedical applications.

    Science.gov (United States)

    Kai, Dan; Liow, Sing Shy; Loh, Xian Jun

    2014-12-01

    Electrospinning has received much attention recently due to the growing interest in nano-technologies and the unique material properties. This review focuses on recent progress in applying electrospinning technique in production of biodegradable nanofibers to the emerging field of biomedical. It first introduces the basic theory and parameters of nanofibers fabrication, with focus on factors affecting the morphology and fiber diameter of biodegradable nanofibers. Next, commonly electrospun biodegradable nanofibers are discussed, and the comparison of the degradation rate of nanoscale materials with macroscale materials are highlighted. The article also assesses the recent advancement of biodegradable nanofibers in different biomedical applications, including tissue engineering, drug delivery, biosensor and immunoassay. Future perspectives of biodegradable nanofibers are discussed in the last section, which emphasizes on the innovation and development in electrospinning of hydrogels nanofibers, pore size control and scale-up productions. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Bio-Based Polymers with Potential for Biodegradability

    Directory of Open Access Journals (Sweden)

    Thomas F. Garrison

    2016-07-01

    Full Text Available A variety of renewable starting materials, such as sugars and polysaccharides, vegetable oils, lignin, pine resin derivatives, and proteins, have so far been investigated for the preparation of bio-based polymers. Among the various sources of bio-based feedstock, vegetable oils are one of the most widely used starting materials in the polymer industry due to their easy availability, low toxicity, and relative low cost. Another bio-based plastic of great interest is poly(lactic acid (PLA, widely used in multiple commercial applications nowadays. There is an intrinsic expectation that bio-based polymers are also biodegradable, but in reality there is no guarantee that polymers prepared from biorenewable feedstock exhibit significant or relevant biodegradability. Biodegradability studies are therefore crucial in order to assess the long-term environmental impact of such materials. This review presents a brief overview of the different classes of bio-based polymers, with a strong focus on vegetable oil-derived resins and PLA. An entire section is dedicated to a discussion of the literature addressing the biodegradability of bio-based polymers.

  5. Making of polymer fine particles

    International Nuclear Information System (INIS)

    Ono, Isamu

    1990-01-01

    The polymer particles having spherical shape and uniform grain diameter are applied to various fields such as powder coating, cosmetics, medicines, foods and others. These polymer fine particles are synthesized from monomers at the temperature higher than room temperature by emulsifying polymerization, suspension polymerization or dispersion polymerization, using polymerization initiator. The diameter of such synthesized fine particles is from 0.1 to 10 μm. In this study, the method of synthesizing polymer fine particles by dispersion radiation polymerization process without using polymerization initiator and emulsifying agent was examined. Monomers are dissolved in the solvent, in which monomers are soluble but polymers are insoluble, and by polymerizing with radiation, polymer fine particles are synthesized. It has the merits that additive agents are not contained, and the synthesis can be done at room temperature. The method and the results are reported. As the mechanism of forming fine particles, the reaction of beginning polymerization and the precipitation of polymers are explained. By controlling reaction temperature and monomer concentration, particle diameter can be adjusted. The monomers used were styrene, methyl metacrylate and vinyl acetate. (K.I.)

  6. A review on introduction and applications of starch and its biodegradable polymers

    OpenAIRE

    Shanta Pokhrel

    2015-01-01

    Biodegradable polymers play a very important role in plastic engineering by replacing non biodegradable, non renewable petrol based polymers. Starch is a renewable, biodegradable, low cost natural polymer with high availability. Natural polymers can be blended with synthetic polymers to improve their properties significantly. This article reviews advance in starch and starch based blends and presents their numerous potential applications. Therefore, this review helps to understand the importa...

  7. Biodegradation of Synthetic Polymers by Composting and Fungal Treatment

    Czech Academy of Sciences Publication Activity Database

    Šašek, Václav; Vitásek, J.; Chromcová, D.; Prokopová, I.; Brožek, J.; Náhlík, J.

    2006-01-01

    Roč. 51, č. 5 (2006), s. 425-430 ISSN 0015-5632 R&D Projects: GA ČR GA203/03/0508 Institutional research plan: CEZ:AV0Z50200510 Keywords : biodegradation * composting * synthetic polymers Subject RIV: EE - Microbiology, Virology Impact factor: 0.963, year: 2006

  8. The use of biodegradable polymers for the stabilization of copper ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 40; Issue 5. The use of biodegradable polymers for the stabilization of copper nanoparticles synthesized by chemical reduction method. ALI OLAD MAHNAZ ... However, agglomerated copper nanoparticles were obtained bythis chemical reduction method. Hence, the ...

  9. Introduction of environmentally degradable parameters to evaluate the biodegradability of biodegradable polymers.

    Science.gov (United States)

    Guo, Wenbin; Tao, Jian; Yang, Chao; Song, Cunjiang; Geng, Weitao; Li, Qiang; Wang, Yuanyuan; Kong, Meimei; Wang, Shufang

    2012-01-01

    Environmentally Degradable Parameter ((Ed)K) is of importance in the describing of biodegradability of environmentally biodegradable polymers (BDPs). In this study, a concept (Ed)K was introduced. A test procedure of using the ISO 14852 method and detecting the evolved carbon dioxide as an analytical parameter was developed, and the calculated (Ed)K was used as an indicator for the ultimate biodegradability of materials. Starch and polyethylene used as reference materials were defined as the (Ed)K values of 100 and 0, respectively. Natural soil samples were inoculated into bioreactors, followed by determining the rates of biodegradation of the reference materials and 15 commercial BDPs over a 2-week test period. Finally, a formula was deduced to calculate the value of (Ed)K for each material. The (Ed)K values of the tested materials have a positive correlation to their biodegradation rates in the simulated soil environment, and they indicated the relative biodegradation rate of each material among all the tested materials. Therefore, the (Ed)K was shown to be a reliable indicator for quantitatively evaluating the potential biodegradability of BDPs in the natural environment.

  10. Introduction of Environmentally Degradable Parameters to Evaluate the Biodegradability of Biodegradable Polymers

    Science.gov (United States)

    Yang, Chao; Song, Cunjiang; Geng, Weitao; Li, Qiang; Wang, Yuanyuan; Kong, Meimei; Wang, Shufang

    2012-01-01

    Environmentally Degradable Parameter (Ed K) is of importance in the describing of biodegradability of environmentally biodegradable polymers (BDPs). In this study, a concept Ed K was introduced. A test procedure of using the ISO 14852 method and detecting the evolved carbon dioxide as an analytical parameter was developed, and the calculated Ed K was used as an indicator for the ultimate biodegradability of materials. Starch and polyethylene used as reference materials were defined as the Ed K values of 100 and 0, respectively. Natural soil samples were inoculated into bioreactors, followed by determining the rates of biodegradation of the reference materials and 15 commercial BDPs over a 2-week test period. Finally, a formula was deduced to calculate the value of Ed K for each material. The Ed K values of the tested materials have a positive correlation to their biodegradation rates in the simulated soil environment, and they indicated the relative biodegradation rate of each material among all the tested materials. Therefore, the Ed K was shown to be a reliable indicator for quantitatively evaluating the potential biodegradability of BDPs in the natural environment. PMID:22675455

  11. Microencapsulation of mildronate in biodegradable and non-biodegradable polymers.

    Science.gov (United States)

    Loca, Dagnija; Sevostjanovs, Eduards; Makrecka, Marina; Zharkova-Malkova, Olga; Berzina-Cimdina, Liga; Tupureina, Velta; Sokolova, Marina

    2014-01-01

    The extremely high hygroscopicity (solubility in water ≥2 g/ml) of the pharmaceutical preparation mildronate defines specific requirements to both packaging material and storage conditions. To overcome the above mentioned inconveniences, microencapsulated form of mildronate was developed using polystyrene (PS) and poly (lactic acid) (PLA) as watertight coating materials. Drug/polymer interaction as well as influence of the microencapsulation process variables on microparticle properties was studied in detail. Water-in-oil-in-water double emulsion technique was adapted and applied for the preparation of PS/mildronate microparticles with total drug load up to 77 %wt and PLA/mildronate microparticles with total drug load up to 80 %wt. The repeatability of the microencapsulation process was ±4% and the encapsulation efficiency of the active ingredient reached 60 %wt. The drug release kinetics from the obtained microparticles was evaluated and it was found that drug release in vivo could be successfully sustained if polystyrene matrix has been used.

  12. Novel biodegradable polymers for local growth factor delivery.

    Science.gov (United States)

    Amsden, Brian

    2015-11-01

    Growth factors represent an important therapeutic protein drug class, and would benefit significantly from formulations that provide sustained, local release to realize their full clinical potential. Biodegradable polymer-based delivery platforms have been examined to achieve this end; however, formulations based on conventional polymers have yet to yield a clinical product. This review examines new polymer biomaterials that have been developed for growth factor delivery. The dosage forms are discussed in terms of their mechanism of release, the stability of the released growth factor, their method of preparation, and their potential for clinical translation. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Resonant infrared pulsed laser deposition of thin biodegradable polymer films

    DEFF Research Database (Denmark)

    Bubb, D.M.; Toftmann, B.; Haglund Jr., R.F.

    2002-01-01

    Thin films of the biodegradable polymer poly(DL-lactide-co-glycolide) (PLGA) were deposited using resonant infrared pulsed laser deposition (RIR-PLD). The output of a free-electron laser was focused onto a solid target of the polymer, and the films were deposited using 2.90 (resonant with O...... absorbance spectrum of the films is nearly identical with that of the native polymer, the average molecular weight of the films is a little less than half that of the starting material. Potential strategies for defeating this mass change are discussed....

  14. Enhancing blood compatibility of biodegradable polymers by introducing sulfobetaine.

    Science.gov (United States)

    Cao, Jun; Chen, Yuan-Wei; Wang, Xin; Luo, Xiang-Lin

    2011-06-15

    Novel biodegradable polycaprolactone containing N,N'-bis (2-hydroxyethyl) methylamine ammonium propane sulfonate (PCL-APS) was synthesized by ring-opening polymerization. The resulting polymers were characterized by nuclear magnetic resonance spectrum (NMR), Fourier transform infrared (FTIR) spectroscopy, gel permeation chromatograph (GPC), differential scanning calorimetry (DSC), and water contact angle (WCA). These measurements showed that the APS unit was introduced into polymers. The hydrolysis of PCL-APS was evaluated by soaking the polymer membranes in a pH = 3.20 acid solution. The rate of weight loss was increased with the content of APS increasing in polymer. The compatibility of polymers were evaluated by platelet adhesion, hemolytic test, and activated partial thromboplastic time (APTT) and prothrombin time (PT) experiments. Results showed that adhered platelets deceased after introducing sulfobetaine as compared to the control PCL, little hemolysis took place on PCL-APS, and APTT of PCL-APS polymers was prolonged than that of control PCL. Therefore, polycaprolactone containing sulfobetaine is a promising biodegradable polymer with good blood compatibility. Copyright © 2011 Wiley Periodicals, Inc.

  15. Biodegradability and biodegradation rate of poly(caprolactone)-starch blend and poly(butylene succinate) biodegradable polymer under aerobic and anaerobic environment.

    Science.gov (United States)

    Cho, H S; Moon, H S; Kim, M; Nam, K; Kim, J Y

    2011-03-01

    The biodegradability and the biodegradation rate of two kinds biodegradable polymers; poly(caprolactone) (PCL)-starch blend and poly(butylene succinate) (PBS), were investigated under both aerobic and anaerobic conditions. PCL-starch blend was easily degraded, with 88% biodegradability in 44 days under aerobic conditions, and showed a biodegradation rate of 0.07 day(-1), whereas the biodegradability of PBS was only 31% in 80 days under the same conditions, with a biodegradation rate of 0.01 day(-1). Anaerobic bacteria degraded well PCL-starch blend (i.e., 83% biodegradability for 139 days); however, its biodegradation rate was relatively slow (6.1 mL CH(4)/g-VS day) compared to that of cellulose (13.5 mL CH(4)/g-VS day), which was used as a reference material. The PBS was barely degraded under anaerobic conditions, with only 2% biodegradability in 100 days. These results were consistent with the visual changes and FE-SEM images of the two biodegradable polymers after the landfill burial test, showing that only PCL-starch blend had various sized pinholes on the surface due to attack by microorganisms. This result may be use in deciding suitable final disposal approaches of different types of biodegradable polymers in the future. Copyright © 2010 Elsevier Ltd. All rights reserved.

  16. Effect of Material Parameters on Mechanical Properties of Biodegradable Polymers/Nanofibrillated Cellulose (NFC) Nano Composites

    Science.gov (United States)

    Yottha Srithep; Ronald Sabo; Craig Clemons; Lih-Sheng Turng; Srikanth Pilla; Jun Peng

    2012-01-01

    Using natural cellulosic fibers as fillers for biodegradable polymers can result in fully biodegradable composites. Biodegradable composites were prepared using nanofibrillated cellulose (NFC) as the reinforcement and poly (3-hydroxybutyrate-co-3-hydroxyvalerate, PHBV) as the polymer matrix. The objective of this study was to determine how various additives (i.e.,...

  17. Targeted Gene Delivery to Macrophages by Biodegradable Star-Shaped Polymers.

    Science.gov (United States)

    Zhang, Yajie; Wang, Yafeng; Zhang, Chi; Wang, Jin; Pan, Dejing; Liu, Jianghuai; Feng, Fude

    2016-02-17

    In this report, two biodegradable star-shaped polyasparamide derivatives and four analogues modified with either mannose or folic acid moiety for preferential targeting of a difficult-to-transfect immune cell type, i.e., macrophage, have been synthesized. Each of the prepared star polymers complexes with plasmid DNA to form nanosized particles featuring a core-shell-like morphology. Mannose or folate functionalized star polymers can greatly improve the transfection performance on a macrophage cell line RAW 264.7. As a result, a combination of targeting ligand modification and topological structures of gene carriers is a promising strategy for immune cells-based gene therapy.

  18. Biodegradable thermogelling polymers: working towards clinical applications.

    Science.gov (United States)

    Dou, Qing Qing; Liow, Sing Shy; Ye, Enyi; Lakshminarayanan, Rajamani; Loh, Xian Jun

    2014-07-01

    As society ages, aging medical problems such as organ damage or failure among senior citizens increases, raising the demand for organ repair technologies. Synthetic materials have been developed and applied in various parts of human body to meet the biomedical needs. Hydrogels, in particular, have found extensive applications as wound healing, drug delivery and controlled release, and scaffold materials in the human body. The development of the next generation of soft hydrogel biomaterials focuses on facile synthetic methods, efficacy of treatment, and tunable multi-functionalities for applications. Supramolecular 3D entities are highly attractive materials for biomedical application. They are assembled by modules via various non-covalent bonds (hydrogen bonds, p-p stacking and/or van der Waals interactions). Biodegradable thermogels are a class of such supramolecular assembled materials. Their use as soft biomaterials and their related applications are described in this Review. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Protection of marble surfaces by using biodegradable polymers as coating agent

    OpenAIRE

    Ocak, Yılmaz; Sofuoğlu, Aysun; Tıhmınlıoğlu, Funda; Böke, Hasan

    2009-01-01

    Biodegradable polymers have been replaced over the synthetic polymers in many applications due to their good properties such as reversibility and biodegradability. Therefore they allow new treatment on the surface of the material to be protected and they fulfil the principles generally accepted by the International Conservation Community of Historic Monuments and Buildings. In this study, the efficiency of four different biodegradable polymers as protective coatings on marble-SO2 reaction was...

  20. Manufacture of porous biodegradable polymer conduits by an extrusion process for guided tissue regeneration

    Science.gov (United States)

    Widmer, M. S.; Gupta, P. K.; Lu, L.; Meszlenyi, R. K.; Evans, G. R.; Brandt, K.; Savel, T.; Gurlek, A.; Patrick, C. W. Jr; Mikos, A. G.; hide

    1998-01-01

    We have fabricated porous, biodegradable tubular conduits for guided tissue regeneration using a combined solvent casting and extrusion technique. The biodegradable polymers used in this study were poly(DL-lactic-co-glycolic acid) (PLGA) and poly(L-lactic acid) (PLLA). A polymer/salt composite was first prepared by a solvent casting process. After drying, the composite was extruded to form a tubular construct. The salt particles in the construct were then leached out leaving a conduit with an open-pore structure. PLGA was studied as a model polymer to analyze the effects of salt weight fraction, salt particle size, and processing temperature on porosity and pore size of the extruded conduits. The porosity and pore size were found to increase with increasing salt weight fraction. Increasing the salt particle size increased the pore diameter but did not affect the porosity. High extrusion temperatures decreased the pore diameter without altering the porosity. Greater decrease in molecular weight was observed for conduits manufactured at higher temperatures. The mechanical properties of both PLGA and PLLA conduits were tested after degradation in vitro for up to 8 weeks. The modulus and failure strength of PLLA conduits were approximately 10 times higher than those of PLGA conduits. Failure strain was similar for both conduits. After degradation for 8 weeks, the molecular weights of the PLGA and PLLA conduits decreased to 38% and 43% of the initial values, respectively. However, both conduits maintained their shape and did not collapse. The PLGA also remained amorphous throughout the time course, while the crystallinity of PLLA increased from 5.2% to 11.5%. The potential of seeding the conduits with cells for transplantation or with biodegradable polymer microparticles for drug delivery was also tested with dyed microspheres. These porous tubular structures hold great promise for the regeneration of tissues which require tubular scaffolds such as peripheral nerve

  1. Radiation processing of biodegradable polymer and hydrogel

    International Nuclear Information System (INIS)

    Yoshii, Fumio

    2000-01-01

    Poly(ε-caprolactone), PCL, (melting temperature 60degC) was gamma-irradiated in the solid state at 30 to 55degC, the molten state, and the supercooled state(irradiation at 45 to 55degC after melting, 80degC) under vacuum to improve its heat resistance. Irradiation of PCL in the supercooled state led to the highest gel content and this polymer has high heat resistance. On the other hand, relatively smaller doses such as 15 and 30 kGy were effective to improve processability of PCL by formation of branch structure during irradiation. It was found that carboxymethylcellulose with relatively high degree of substitution led crosslinking at high concentration in aqueous solution such as 10% by irradiation. (author)

  2. Liquid marble formation and solvent vapor treatment of the biodegradable polymers polylactic acid and polycaprolactone.

    Science.gov (United States)

    Schmücker, Christoph; Stevens, Geoffrey W; Mumford, Kathryn A

    2018-03-15

    Liquid Marbles were produced by rolling aqueous droplets on a powder bed of biodegradable polymers, namely polylactic acid (PLA), polycaprolactone (PCL) and blends of these. Solvent vapor treatment was subsequently applied with dichloromethane (DCM). This treatment aligned the polymer chains in order to form a smooth polymeric shell with enhanced mechanical and barrier properties. Whilst a wide range of potential applications for Liquid Marbles exists, the aim here is to encapsulate a solution containing a fertilizer, i.e. urea to produce a controlled release fertilizer. The influences of droplet volume, polymer particle size and solvent vapor treatment time on the liquid marble properties were investigated. Crystallinity and thermal properties were analyzed by differential scanning calorimetry (DSC), surface characteristics and shell thickness by scanning electron microscopy (SEM), mechanical strength and elasticity by compression tests and evaporation rates by thermogravimetric analysis (TGA). Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Biodegradable Polymer-Based Scaffolds for Bone Tissue Engineering

    CERN Document Server

    Sultana, Naznin

    2013-01-01

    This book addresses the principles, methods and applications of biodegradable polymer based scaffolds for bone tissue engineering. The general principle of bone tissue engineering is reviewed and the traditional and novel scaffolding materials, their properties and scaffold fabrication techniques are explored. By acting as temporary synthetic extracellular matrices for cell accommodation, proliferation, and differentiation, scaffolds play a pivotal role in tissue engineering. This book does not only provide the comprehensive summary of the current trends in scaffolding design but also presents the new trends and directions for scaffold development for the ever expanding tissue engineering applications.

  4. The Recent Developments in Biobased Polymers toward General and Engineering Applications : Polymers that Are Upgraded from Biodegradable Polymers, Analogous to Petroleum-Derived Polymers, and Newly Developed

    NARCIS (Netherlands)

    Nakajima, Hajime; Dijkstra, Peter; Loos, Katja

    2017-01-01

    The main motivation for development of biobased polymers was their biodegradability, which is becoming important due to strong public concern about waste. Reflecting recent changes in the polymer industry, the sustainability of biobased polymers allows them to be used for general and engineering

  5. The use of biodegradable polymers in design of cellular scaffolds.

    Science.gov (United States)

    Orłowska, Joanna; Kurczewska, Urszula; Derwińska, Katarzyna; Orłowski, Wojciech; Orszulak-Michalak, Daria

    2015-03-05

    The objective of this work was to demonstrate the usage of biodegradable polymers, made of calcium alginate and dibutyrylchitin, in the design of cellular scaffolds having broad application in reconstructive therapy (dentistry, orthopedics). To visualize cells seeded on calcium alginate and dibutyrylchitin polymers DAPI staining of fibroblasts nuclei was used. The cytotoxicity of the materials and microscopic evaluation of the viability of seeded cells was tested with a PKH 67 fluorescent dye. To assess the cellular toxicity the proliferation of fibroblasts adjacent to the tested polymers was examined. The vitability of cells seeded on polymers was also evaluated by measuring the fluorescence intensity of calcein which binds only to live cells. The conducted experiments (DAPI and PKH 67 staining) show that the tested materials have a positive influence on cell adhesion crucial for wound healing - fibroblasts. The self-made dibutyrylchitin dressing do not cause the reduction of viability of cells seeded on them. The in vitro study illustrated the interactions between the tested materials, constructed of calcium alginate or dibutyrylchitin and mouse fibroblasts and proved their usefulness in the design of cellular scaffolds. Examined polymers turned out to be of great interest and promise for cellular scaffolds design.

  6. The use of biodegradable polymers in design of cellular scaffolds

    Directory of Open Access Journals (Sweden)

    Joanna Orłowska

    2015-03-01

    Full Text Available The objective of this work was to demonstrate the usage of biodegradable polymers, made of calcium alginate and dibutyrylchitin, in the design of cellular scaffolds having broad application in reconstructive therapy (dentistry, orthopedics. To visualize cells seeded on calcium alginate and dibutyrylchitin polymers DAPI staining of fibroblasts nuclei was used. The cytotoxicity of the materials and microscopic evaluation of the viability of seeded cells was tested with a PKH 67 fluorescent dye. To assess the cellular toxicity the proliferation of fibroblasts adjacent to the tested polymers was examined. The vitability of cells seeded on polymers was also evaluated by measuring the fluorescence intensity of calcein which binds only to live cells. The conducted experiments (DAPI and PKH 67 staining show that the tested materials have a positive influence on cell adhesion crucial for wound healing – fibroblasts. The self-made dibutyrylchitin dressing do not cause the reduction of viability of cells seeded on them. The in vitro study illustrated the interactions between the tested materials, constructed of calcium alginate or dibutyrylchitin and mouse fibroblasts and proved their usefulness in the design of cellular scaffolds. Examined polymers turned out to be of great interest and promise for cellular scaffolds design.

  7. Characterization of biodegradable polymers irradiated with swift heavy ions

    International Nuclear Information System (INIS)

    Salguero, N.G.; Grosso, M.F. del; Durán, H.; Peruzzo, P.J.; Amalvy, J.I.

    2012-01-01

    In view of their application as biomaterials, there is an increasing interest in developing new methods to induce controlled cell adhesion onto polymeric materials. The critical step in all these methods involves the modification of polymer surfaces, to induce cell adhesion, without changing theirs degradation and biocompatibility properties. In this work two biodegradable polymers, polyhydroxybutyrate (PHB) and poly-L-lactide acid (PLLA) were irradiated using carbon and sulfur beams with different energies and fluences. Pristine and irradiated samples were degradated by immersion in a phosphate buffer at pH 7.0 and then characterized. The analysis after irradiation and degradation showed a decrease in the contact angle values and changes in their crystallinity properties.

  8. Characterization of biodegradable polymers irradiated with swift heavy ions

    Energy Technology Data Exchange (ETDEWEB)

    Salguero, N.G. [Gerencia de Investigacion y Aplicaciones, TANDAR-CNEA, Av. Gral. Paz 1499 (B1650KNA) San Martin, Buenos Aires (Argentina); Grosso, M.F. del, E-mail: delgrosso@tandar.cnea.gov.ar [Gerencia de Investigacion y Aplicaciones, TANDAR-CNEA, Av. Gral. Paz 1499 (B1650KNA) San Martin, Buenos Aires (Argentina); CONICET, Av. Rivadavia 1917 C1033AAJ CABA (Argentina); Duran, H. [CONICET, Av. Rivadavia 1917 C1033AAJ CABA (Argentina); Gerencia de Desarrollo Tecnologico y Proyectos Especiales, CNEA, Av. Gral. Paz 1499 (B1650KNA) San Mart Latin-Small-Letter-Dotless-I Acute-Accent n, Buenos Aires (Argentina); Escuela de Ciencia y Tecnologia, H. Yrigoyen 3100, CP 1650, San Martin, UNSAM (Argentina); Peruzzo, P.J. [CICPBA - Grupo de Materiales y Nanomateriales Polimericos, Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas (INIFTA), CCT La Plata CONICET - Universidad Nacional de La Plata, La Plata (Argentina); Amalvy, J.I. [CICPBA - Grupo de Materiales y Nanomateriales Polimericos, Instituto de Investigaciones Fisicoquimicas Teoricas y Aplicadas (INIFTA), CCT La Plata CONICET - Universidad Nacional de La Plata, La Plata (Argentina); Facultad de Ingenieria, Universidad Nacional de La Plata, Calle 116 y 48 (B1900TAG), La Plata (Argentina); Departamento de Ingenieria Quimica, Facultad Regional La Plata, Universidad Tecnologica Nacional, 60 y 124 (1900), La Plata (Argentina); and others

    2012-02-15

    In view of their application as biomaterials, there is an increasing interest in developing new methods to induce controlled cell adhesion onto polymeric materials. The critical step in all these methods involves the modification of polymer surfaces, to induce cell adhesion, without changing theirs degradation and biocompatibility properties. In this work two biodegradable polymers, polyhydroxybutyrate (PHB) and poly-L-lactide acid (PLLA) were irradiated using carbon and sulfur beams with different energies and fluences. Pristine and irradiated samples were degradated by immersion in a phosphate buffer at pH 7.0 and then characterized. The analysis after irradiation and degradation showed a decrease in the contact angle values and changes in their crystallinity properties.

  9. Characterization of biodegradable polymers irradiated with swift heavy ions

    Science.gov (United States)

    Salguero, N. G.; del Grosso, M. F.; Durán, H.; Peruzzo, P. J.; Amalvy, J. I.; Arbeitman, C. R.; García Bermúdez, G.

    2012-02-01

    In view of their application as biomaterials, there is an increasing interest in developing new methods to induce controlled cell adhesion onto polymeric materials. The critical step in all these methods involves the modification of polymer surfaces, to induce cell adhesion, without changing theirs degradation and biocompatibility properties. In this work two biodegradable polymers, polyhydroxybutyrate (PHB) and poly- L-lactide acid (PLLA) were irradiated using carbon and sulfur beams with different energies and fluences. Pristine and irradiated samples were degradated by immersion in a phosphate buffer at pH 7.0 and then characterized. The analysis after irradiation and degradation showed a decrease in the contact angle values and changes in their crystallinity properties.

  10. Radiation processing of biodegradable polymer hydrogel from cellulose derivatives

    International Nuclear Information System (INIS)

    Wach, Radoslaw A.; Mitomo, Hiroshi; Yoshii, Fumio; Kume, Tamikazu

    2001-01-01

    The effects of high-energy radiation on ethers of cellulose: carboxymethyl-, hydroxypropyl- and hydroxyethylcellulose have been investigated. Polymers were irradiated in solid state and aqueous solution at various concentrations. Degree of substitution (DS), the concentration in the solution and irradiation conditions had a significant impact on the obtained products. Irradiation of polymers in solid and in diluted solution resulted in their degradation. A novel hydrogels of such natural polymers were synthesized, without using any additives, by irradiation at high concentration. It was found that high DS of CMC promoted crosslinking and, for all of the ethers, the gel formation occurred easier for more concentrated solutions. Paste-like form of the initial material, when water plasticised the bulk of polymer mass, along with the high dose rate and preventing oxygen accessibility to the sample during irradiation were favorable for hydrogel preparation. Up to 95% of gel fraction was obtained from 50 and 60% CMC solutions irradiated by gamma rays or by a beam of accelerated electrons (EB). The other polymers were more sensitive to the dose rate and formed gels with higher gel fraction while processed by EB. Moreover, polymers (except CMC) treated by gamma rays were susceptible to degradation after application of a dose over 50-100 kGy. The presence of oxygen in the system during irradiation limited a gel content and was prone to easier degradation of already formed gel. Produced hydrogels swelled markedly by absorption when paced in the solvent. Crosslinked polymers showed susceptibility to degradation by cellulase enzyme and by the action of microorganisms in compost or under natural conditions in soil thus could be included into the group of biodegradable materials. (author)

  11. Radiation processing of biodegradable polymer hydrogel from cellulose derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Wach, Radoslaw A.; Mitomo, Hiroshi [Gunma Univ., Faculty of Engineering, Department of Biological and Chemical Engineering, Kiryu, Gunma (Japan); Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

    2001-03-01

    The effects of high-energy radiation on ethers of cellulose: carboxymethyl-, hydroxypropyl- and hydroxyethylcellulose have been investigated. Polymers were irradiated in solid state and aqueous solution at various concentrations. Degree of substitution (DS), the concentration in the solution and irradiation conditions had a significant impact on the obtained products. Irradiation of polymers in solid and in diluted solution resulted in their degradation. A novel hydrogels of such natural polymers were synthesized, without using any additives, by irradiation at high concentration. It was found that high DS of CMC promoted crosslinking and, for all of the ethers, the gel formation occurred easier for more concentrated solutions. Paste-like form of the initial material, when water plasticised the bulk of polymer mass, along with the high dose rate and preventing oxygen accessibility to the sample during irradiation were favorable for hydrogel preparation. Up to 95% of gel fraction was obtained from 50 and 60% CMC solutions irradiated by gamma rays or by a beam of accelerated electrons (EB). The other polymers were more sensitive to the dose rate and formed gels with higher gel fraction while processed by EB. Moreover, polymers (except CMC) treated by gamma rays were susceptible to degradation after application of a dose over 50-100 kGy. The presence of oxygen in the system during irradiation limited a gel content and was prone to easier degradation of already formed gel. Produced hydrogels swelled markedly by absorption when paced in the solvent. Crosslinked polymers showed susceptibility to degradation by cellulase enzyme and by the action of microorganisms in compost or under natural conditions in soil thus could be included into the group of biodegradable materials. (author)

  12. Mucosal delivery of vaccines: role of mucoadhesive/biodegradable polymers.

    Science.gov (United States)

    Garg, Neeraj K; Mangal, Sharad; Khambete, Hemant; Sharma, Pradeep K; Tyagi, Rajeev K

    2010-06-01

    Majority of infectious microorganism make their gateway to the host through mucosal surfaces, such as gastrointestinal tract, nasal and vaginal tract. Mucosal immune response structured as sIgA can effectively prevent the attachment and invasion of the microorganism from mucosal surface and thereby serves as an efficient tool against infectious disease. There has been an increased demand for the development of novel vaccine that leads to the induction of immune response in systemic circulation as well as at mucosal surfaces against infectious disease. Mucosal delivery of vaccine provides basis for induction of both mucosal as well as systemic immune responses against the infectious organisms. However, a variety of factors such as mucociliary clearance, presence of deteriorating enzymes, pH extremes (GIT), low permeation and metabolic degradation limit the mucosal delivery of vaccine. Numerous strategies have been explored in the meadow of mucosal vaccination for the purpose of efficient antigen delivery through mucosal route(s). Polymeric carrier(s) such as nanoparticles and microparticles loaded with the antigen can serve as the basis for creation of important formulations for improved vaccine. Biodegradable and mucoadhesive polymeric carrier(s) seems to be most promising candidate for mucosal vaccine delivery. Several polymers from natural and synthetic origin, such as polylactide-co-glycolide, chitosan, alginate, carbopol, gelatin etc., have been explored for the efficient mucosal vaccine delivery and significant results have been obtained. This review outlines the polymers used in mucosal vaccine delivery with special reference to mucoadhesive/biodegradable polymers. This article also covers the recent patent granted in the field on polymeric carrier mediated mucosal vaccination.

  13. The Recent Developments in Biobased Polymers toward General and Engineering Applications: Polymers that Are Upgraded from Biodegradable Polymers, Analogous to Petroleum-Derived Polymers, and Newly Developed

    OpenAIRE

    Nakajima, Hajime; Dijkstra, Peter; Loos, Katja

    2017-01-01

    The main motivation for development of biobased polymers was their biodegradability, which is becoming important due to strong public concern about waste. Reflecting recent changes in the polymer industry, the sustainability of biobased polymers allows them to be used for general and engineering applications. This expansion is driven by the remarkable progress in the processes for refining biomass feedstocks to produce biobased building blocks that allow biobased polymers to have more versati...

  14. Micro fabrication of biodegradable polymer drug delivery devices

    DEFF Research Database (Denmark)

    Nagstrup, Johan

    . Furthermore, they are often degraded before they can be absorbed. The result is low bioavailability of the drugs. To overcome these challenges, better drug delivery systems need to be developed. Recently, micro systems have emerged as promising candidates to solve the challenges of poor solubility, low......The pharmaceutical industry is presently facing several obstacles in developing oral drug delivery systems. This is primarily due to the nature of the discovered drug candidates. The discovered drugs often have poor solubility and low permeability across the gastro intestinal epithelium...... permeability and degradation. These systems are for the majority based on traditional materials used in micro technology, such as SU-8, silicon, poly(methyl methacrylate). The next step in developing these new drug delivery systems is to replace classical micro fabrication materials with biodegradable polymers...

  15. Sintered iron biodegradable materials modified by polymer coating

    International Nuclear Information System (INIS)

    Gorejova, R.; Markusova-Buckova, L.; Orinakova, R.

    2017-01-01

    Devices made from biodegradable materials become a promising alternative to a permanent orthopedic implants. Temporary scaffolds made from these materials can provide desirable results in tissue healing and gradually dissolve in vivo by corrosion processes. This work is dedicated to preparation of iron based metallic structures prepared by powder metallurgy which were modified by polyethyleneglycol (PEG) coatings in different concentration. Corrosion behaviour of the prepared samples was observed in the form of static corrosion and dynamic corrosion in Hank's solution. Results show that the rate of degradation of polymer coated samples was greater than rate of degradation of pure iron. The highest rate of degradation was observed in porous structure covered with PEG with a concentration of 10 wt. %. (authors)

  16. Biolimus-eluting biodegradable polymer-coated stent versus durable polymer-coated sirolimus-eluting stent in unselected patients receiving percutaneous coronary intervention (SORT OUT V)

    DEFF Research Database (Denmark)

    Christiansen, Evald Høj; Jensen, Lisette Okkels; Thayssen, Per

    2013-01-01

    Third-generation biodegradable polymer drug-eluting stents might reduce the risk of stent thrombosis compared with first-generation permanent polymer drug-eluting stents. We aimed to further investigate the effects of a biodegradable polymer biolimus-eluting stent compared with a durable polymer...

  17. Synthesis of Biodegradable Polymer Micro- and Nanoparticles for Controlled Drug Delivery by Multiplexed Electrosprays

    Science.gov (United States)

    Almeria, Begona

    The goal of controlled drug delivery is to administer sustained amounts of a therapeutic agent over a prolonged period of time, improving the drug efficacy as compared to conventional, bolus doses that lead to variable concentrations of drug in blood. Although there are several systems capable to provide such a continuous-dose-based treatment, the use of biodegradable polymer micro- and, especially, nanoparticles offers multiple advantages with respect to other platforms. Their small size allows them to pass through physical barriers in the body and reach the site of treatment, allowing for a localized delivery, reducing side effects and toxicity. Polymer nanoparticles have lower clearance by the immune system, and are especially useful in intracellular delivery, delivery to the lymphatic system and the treatment of tumors, where the site of treatment is difficult to reach by larger particles. Conventional methods for biodegradable particle production rely predominately on batch, emulsion preparation methods and suffer from several shortcomings: low encapsulation efficiency (˜10% for hydrophilic drugs), difficulty to generate sufficiently small (dthe micro scale, and poor repeatability. We have developed an alternative process based on electrospray (ES) that offers distinct advantages and overcomes all of these limitations. We demonstrate this process with the Poly(DL-lactic-co-glycolic acid) (PLGA) system encapsulating agents such as Doxorubicin, Rhodamine B and Rhodamine B octadecyl ester prechlorate. We also employ this method for the generation of theranostic systems that combine their therapeutic mission with imaging capabilities to detect the biodistribution of particles inside the body. PLGA microparticles in different sizes, morphologies and compactness are generated using the electrospray-drying route. The size of the synthesized particles is primarily controlled by the delicate tuning of the solution physical properties and the ES operational parameters

  18. Implantable biodegradable polymers for radiosensitization of human glioma in vivo

    International Nuclear Information System (INIS)

    Williams, Jeffery; Dillehay, Larry E.; Sipos, Eric; Fahlman, Christian; Tabassi, Kevin; Williams, Jerry; Wharam, Moody; Brem, Henry

    1995-01-01

    Purpose: The potential of halogenated pyrimidines to radiosensitize human gliomas remains unrealized. Higher local delivery and lower systemic exposure may improve the therapeutic ratio. Synthetic, implantable, biodegradable polyanhydride polymers allow local, controlled, and sustained release of therapeutic agents. Their role in radiosensitization of tumors remains unexplored, however. Materials and Methods: In vitro: To measure release, increasing (10%, 30%, 50%) proportions of 5-iodo-2'-deoxyuridine (IUdR) in synthetic [(poly(bis(p-carboxyphenoxy)-propane) (PCPP):sebacic acid (SA) (PCPP:SA ratio 20:80)]polymers (ca. 10 mg; 1x1x3 mm) were incubated (1 ml PBS, 37 deg. C) and the supernatants serially assayed using HPLC. To measure modulation of release by a second, inert, co-loaded compound, 5-125-I-2'-deoxyuridine (125-IUdR) and increasing (10%, 30%, or 50%) proportions of D-glucose were combined in polymers, incubated in PBS, and the supernatants assayed. To test radiosensitization, cells (U251 human malignant glioma) were sequentially exposed to increasing (0, 0.1, 1.0, or 10 uM) concentrations of IUdR and increasing (0, 2.5, 5.0, or 10 Gy) doses of acute radiation. In vivo: To measure release, polymers bearing 125-IUdR were surgically placed in U251 xenografts (0.1 - 0.2 cc) growing in flanks of nude mice. The flanks bearing the tumors and polymers were reproducibly positioned over a collimated scintillation detector and counted. To measure radiosensitization, polymers bearing no (blank) or 50% unlabeled IUdR were placed in the tumor or contralateral flank. After three days tumors were acutely irradiated (500 cGy x 2 daily fractions). Results: In vitro: The initial rates of release of IUdR from polymers were high regardless of the percentage loading of IUdR, while the subsequent rates of release were proportionate to the percentage loading. The percentages of loaded IUdR recovered were 21.5, 23.3, and 18.7% in 6 h and 57.0, 73.5, and 92.4% after 11 days for 10

  19. JTEC monograph on biodegradable polymers and plastics in Japan: Research, development, and applications

    Science.gov (United States)

    Lenz, Robert W.

    1995-01-01

    A fact-finding team of American scientists and engineers visited Japan to assess the status of research and development and applications in biodegradable polymers. The visit was sponsored by the National Science Foundation and industry. In Japan, the team met with representatives of 31 universities, government ministries and institutes, companies, and associations. Japan's national program on biodegradable polymers and plastics evaluates new technologies, testing methods, and potential markets for biodegradables. The program is coordinated by the Biodegradable Plastics Society of Japan, which seeks to achieve world leadership in biodegradable polymer technology and identify commercial opportunities for exploiting this technology. The team saw no major new technology breakthroughs. Japanese scientists and engineers are focusing on natural polymers from renewable resources, synthetic polymers, and bacterially-produced polymers such as polyhydroxyalkanoates, poly(amino acids), and polysaccharides. The major polymers receiving attention are the Zeneca PHBV copolymers, Biopol(registered trademark), poly(lactic acid) from several sources, polycaprolactone, and the new synthetic polyester, Bionolle(registered trademark), from Showa High Polymer. In their present state of development, these polymers all have major deficiencies that inhibit their acceptance for large-scale applications.

  20. The SYNERGY biodegradable polymer everolimus eluting coronary stent: Porcine vascular compatibility and polymer safety study.

    Science.gov (United States)

    Wilson, Gregory J; Marks, Angela; Berg, Kimberly J; Eppihimer, Michael; Sushkova, Natalia; Hawley, Steve P; Robertson, Kimberly A; Knapp, David; Pennington, Douglas E; Chen, Yen-Lane; Foss, Aaron; Huibregtse, Barbara; Dawkins, Keith D

    2015-11-15

    SYNERGY is a novel platinum chromium alloy stent that delivers abluminal everolimus from an ultrathin poly-lactide-co-glycide (PLGA) biodegradable polymer. This study evaluated the in vivo degradation of the polymer coating, everolimus release time course, and vascular compatibility of the SYNERGY stent. SYNERGY stents were implanted in arteries of domestic swine. Devices were explanted at predetermined time points (up to 120 days) and the extent of PLGA coating or everolimus remaining on the stents was quantified. Everolimus levels in the arterial tissue were also evaluated. A pathological analysis on coronary arteries of single and overlapping stents was performed at time points between 5 and 270 days. PLGA bioabsorption began immediately after implantation, and drug release was essentially complete by 90 days; PLGA absorption was substantially complete by 120 days (>90% of polymer was absorbed) leaving a bare metal SYNERGY stent. Vascular response was similar among SYNERGY and control stents (bare metal, polymer-only, and 3× polymer-only). Mild increases in para-strut fibrin were seen for SYNERGY at an early time point with no significant differences in all other morphological and morphometric parameters through 270 days or endothelial function (eNOS immunostaining) at 90 or 180 days. Inflammation was predominantly minimal to mild for all device types. In a swine model, everolimus was released by 90 days and PLGA bioabsorption was complete shortly thereafter. The SYNERGY stent and its biodegradable polymer, even at a 3× safety margin, demonstrated vascular compatibility similar to bare metal stent controls. © 2015 Wiley Periodicals, Inc.

  1. Polyester-Based (Bio)degradable Polymers as Environmentally Friendly Materials for Sustainable Development

    Science.gov (United States)

    Rydz, Joanna; Sikorska, Wanda; Kyulavska, Mariya; Christova, Darinka

    2014-01-01

    This review focuses on the polyesters such as polylactide and polyhydroxyalkonoates, as well as polyamides produced from renewable resources, which are currently among the most promising (bio)degradable polymers. Synthetic pathways, favourable properties and utilisation (most important applications) of these attractive polymer families are outlined. Environmental impact and in particular (bio)degradation of aliphatic polyesters, polyamides and related copolymer structures are described in view of the potential applications in various fields. PMID:25551604

  2. Particle networks through aggregation in polymer nanocomposites

    Science.gov (United States)

    Shofner, Meisha; Kaur, Jasmeet; Lee, Ji Hoon

    2011-03-01

    Structure-property research in polymer nanocomposites has often focused on producing systems that are homogeneously dispersed in order to capitalize on the large amount of specific surface area available from nanoparticles. However, inhomogeneous dispersion is often obtained and in some cases has been deliberately sought to enhance functional properties through the formation of particle networks. In this research, we are seeking to understand how particle aggregation impacts network formation in polymer nanocomposites as a function of native particle shape. Specifically, we are characterizing nanocomposites comprised of calcium phosphate particles with different shapes and a polyhydroxybutyrate matrix. Experimental results concerning the effect of particle aggregation and shape on polymer crystalline structure, thermal transitions and mechanical properties are presented to correlate particle aggregation to network formation and understand structure-property relationships in these materials.

  3. Biodegradation of New Polymer Foundry Binders for the Example of the Composition Polyacrylic Acid/Starch

    Directory of Open Access Journals (Sweden)

    Beata Grabowska

    2011-04-01

    Full Text Available The investigations on the biodegradation process pathway of the new polymer binders for the example of water soluble compositionpolyacrylic acid/starch are presented in the hereby paper. Degradation was carried out in water environment and in a soil. Thedetermination of the total oxidation biodegradation in water environment was performed under laboratory conditions in accordance with the static water test system (Zahn-Wellens method, in which the mixture undergoing biodecomposition contained inorganic nutrient,activated sludge and the polymer composition, as the only carbon and energy source. The biodecomposition progress of the polymercomposition sample in water environment was estimated on the basis of the chemical oxygen demand (COD measurements and thedetermination the biodegradation degree, Rt, during the test. These investigations indicated that the composition polyacrylic acid/starchconstitutes the fully biodegradable material in water environment. The biodegradation degree Rt determined in the last 29th day of the test duration achieved 65%, which means that the investigated polymer composition can be considered to be fully biodegradable.During the 6 months biodegradation process of the cross-linked sample of the polymer composition in a garden soil several analysis ofsurface and structural changes, resulting from the sample decomposition, were performed. Those were: thermal analyses (TG-DSC,structural analyses (Raman spectroscopy and microscopic analyses (optical microscopy, AFM.

  4. Novel bio-based and biodegradable polymer blends

    Science.gov (United States)

    Yang, Shengzhe

    Most plastic materials, including high performance thermoplastics and thermosets are produced entirely from petroleum-based products. The volatility of the natural oil markets and the increasing cost of petroleum have led to a push to reduce the dependence on petroleum products. Together with an increase in environmental awareness, this has promoted the use of alternative, biorenewable, environmentally-friendly products, such as biomass. The growing interest in replacing petroleum-based products by inexpensive, renewable, natural materials is important for sustainable development into the future and will have a significant impact on the polymer industry and the environment. This thesis involved characterization and development of two series of novel bio-based polymer blends, namely polyhydroxyalkanoate (PHA)/polyamide (PA) and poly(lactic acid) (PLA)/soy protein. Blends with different concentrations and compatible microstructures were prepared using twin-screw extruder. For PHA/PA blends, the poor mechanical properties of PHA improved significantly with an excellent combination of strength, stiffness and toughness by adding PA. Furthermore, the effect of blending on the viscoelastic properties has been investigated using small-amplitude oscillatory shear flow experiments as a function of blend composition and angular frequency. The elastic shear modulus (G‧) and complex viscosity of the blends increased significantly with increasing the concentration of PHA. Blending PLA with soy protein aims at reducing production cost, as well as accelerating the biodegradation rate in soil medium. In this work, the mechanical, thermal and morphological properties of the blends were investigated using dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and tensile tests.

  5. Carbon recovery from wastewater through bioconversion into biodegradable polymers.

    Science.gov (United States)

    Valentino, Francesco; Morgan-Sagastume, Fernando; Campanari, Sabrina; Villano, Marianna; Werker, Alan; Majone, Mauro

    2017-07-25

    Polyhydroxyalkanoates (PHA) are biodegradable polyesters that can be produced in bioprocesses from renewable resources in contrast to fossil-based bio-recalcitrant polymers. Research efforts have been directed towards establishing technical feasibility in the use of mixed microbial cultures (MMC) for PHA production using residuals as feedstock, mainly consisting of industrial process effluent waters and wastewaters. In this context, PHA production can be integrated with waste and wastewater biological treatment, with concurrent benefits of resource recovery and sludge minimization. Over the past 15 years, much of the research on MMC PHA production has been performed at laboratory scale in three process elements as follows: (1) acidogenic fermentation to obtain a volatile fatty acid (VFA)-rich stream, (2) a dedicated biomass production yielding MMCs enriched with PHA-storing potential, and (3) a PHA accumulation step where (1) and (2) outputs are combined in a final biopolymer production bioprocess. This paper reviews the recent developments on MMC PHA production from synthetic and real wastewaters. The goals of the critical review are: a) to highlight the progress of the three-steps in MMC PHA production, and as well to recommend room for improvements, and b) to explore the ideas and developments of integration of PHA production within existing infrastructure of municipal and industrial wastewaters treatment. There has been much technical advancement of ideas and results in the MMC PHA rich biomass production. However, clear demonstration of production and recovery of the polymers within a context of product quality over an extended period of time, within an up-scalable commercially viable context of regional material supply, and with well-defined quality demands for specific intent of material use, is a hill that still needs to be climbed in order to truly spur on innovations for this field of research and development. Copyright © 2016 Elsevier B.V. All rights

  6. New biocomposites based on bioplastic flax fibers and biodegradable polymers.

    Science.gov (United States)

    Wróbel-Kwiatkowska, Magdalena; Czemplik, Magdalena; Kulma, Anna; Zuk, Magdalena; Kaczmar, Jacek; Dymińska, Lucyna; Hanuza, Jerzy; Ptak, Maciej; Szopa, Jan

    2012-01-01

    A new generation of entirely biodegradable and bioactive composites with polylactic acid (PLA) or poly-ε-caprolactone (PCL) as the matrix and bioplastic flax fibers as reinforcement were analyzed. Bioplastic fibers contain polyhydroxybutyrate and were obtained from transgenic flax. Biochemical analysis of fibers revealed presence of several antioxidative compounds of hydrophilic (phenolics) and hydrophobic [cannabidiol (CBD), lutein] nature, indicating their high antioxidant potential. The presence of CBD and lutein in flax fibers is reported for the first time. FTIR analysis showed intermolecular hydrogen bonds between the constituents in composite PLA+flax fibers which were not detected in PCL-based composite. Mechanical analysis of prepared composites revealed improved stiffness and a decrease in tensile strength. The viability of human dermal fibroblasts on the surface of composites made of PLA and transgenic flax fibers was the same as for cells cultured without composites and only slightly lower (to 9%) for PCL-based composites. The amount of platelets and Escherichia coli cells aggregated on the surface of the PLA based composites was significantly lower than for pure polymer. Thus, composites made of PLA and transgenic flax fibers seem to have bacteriostatic, platelet anti-aggregated, and non-cytotoxic effect. Copyright © 2012 American Institute of Chemical Engineers (AIChE).

  7. Modern mass spectrometry in the characterization and degradation of biodegradable polymers

    Energy Technology Data Exchange (ETDEWEB)

    Rizzarelli, Paola, E-mail: paola.rizzarelli@cnr.it; Carroccio, Sabrina

    2014-01-15

    Graphical abstract: -- Highlights: •Recent trends in the structural characterization of biodegradable polymers by MALDI and ESI MS are discussed. •MALDI MS as a noteworthy tool to follow the synthetic polymerization route of biodegradable materials is evidenced. •Elucidation of degradation mechanisms by modern MS techniques is examined. •ESI MS and HPLC–ESI MS are highlighted as highly suitable methods for structural and quantitative analysis of water-soluble biodegradation products. •Novel MS methods developed ad hoc and new MALDI matrices for biodegradable polymers are reviewed. -- Abstract: In the last decades, the solid-waste management related to the extensively growing production of plastic materials, in concert with their durability, have stimulated increasing interest in biodegradable polymers. At present, a variety of biodegradable polymers has already been introduced onto the market and can now be competitive with non biodegradable thermoplastics in different fields (packaging, biomedical, textile, etc.). However, a significant economical effort is still directed in tailoring structural properties in order to further broaden the range of applications without impairing biodegradation. Improving the performance of biodegradable materials requires a good characterization of both physico-chemical and mechanical parameters. Polymer analysis can involve many different features including detailed characterization of chemical structures and compositions as well as average molecular mass determination. It is of outstanding importance in troubleshooting of a polymer manufacturing process and for quality control, especially in biomedical applications. This review describes recent trends in the structural characterization of biodegradable materials by modern mass spectrometry (MS). It provides an overview of the analytical tools used to evaluate their degradation. Several successful applications of MALDI-TOF MS (matrix assisted laser desorption ionization

  8. From particle condensation to polymer aggregation

    Science.gov (United States)

    Janke, Wolfhard; Zierenberg, Johannes

    2018-01-01

    We draw an analogy between droplet formation in dilute particle and polymer systems. Our arguments are based on finite-size scaling results from studies of a two-dimensional lattice gas to three-dimensional bead-spring polymers. To set the results in perspective, we compare with in part rigorous theoretical scaling laws for canonical condensation in a supersaturated gas at fixed temperature, and derive corresponding scaling predictions for an undercooled gas at fixed density. The latter allows one to efficiently employ parallel multicanonical simulations and to reach previously not accessible scaling regimes. While the asymptotic scaling can not be observed for the comparably small polymer system sizes, they demonstrate an intermediate scaling regime also observable for particle condensation. Altogether, our extensive results from computer simulations provide clear evidence for the close analogy between particle condensation and polymer aggregation in dilute systems.

  9. Modern mass spectrometry in the characterization and degradation of biodegradable polymers.

    Science.gov (United States)

    Rizzarelli, Paola; Carroccio, Sabrina

    2014-01-15

    In the last decades, the solid-waste management related to the extensively growing production of plastic materials, in concert with their durability, have stimulated increasing interest in biodegradable polymers. At present, a variety of biodegradable polymers has already been introduced onto the market and can now be competitive with non biodegradable thermoplastics in different fields (packaging, biomedical, textile, etc.). However, a significant economical effort is still directed in tailoring structural properties in order to further broaden the range of applications without impairing biodegradation. Improving the performance of biodegradable materials requires a good characterization of both physico-chemical and mechanical parameters. Polymer analysis can involve many different features including detailed characterization of chemical structures and compositions as well as average molecular mass determination. It is of outstanding importance in troubleshooting of a polymer manufacturing process and for quality control, especially in biomedical applications. This review describes recent trends in the structural characterization of biodegradable materials by modern mass spectrometry (MS). It provides an overview of the analytical tools used to evaluate their degradation. Several successful applications of MALDI-TOF MS (matrix assisted laser desorption ionization time of flight) and ESI MS (electrospray mass spectrometry) for the determination of the structural architecture of biodegradable macromolecules, including their topology, composition, chemical structure of the end groups have been reported. However, MS methodologies have been recently applied to evaluate the biodegradation of polymeric materials. ESI MS represents the most useful technique for characterizing water-soluble polymers possessing different end group structures, with the advantage of being easily interfaced with solution-based separation techniques such as high-performance liquid

  10. [Progress and prospect of synthetic biodegradable polymers for bone repair and reconstruction].

    Science.gov (United States)

    Zhao, Zenghui; Jiang, Dianming

    2010-03-01

    To review the latest researches of synthetic biodegradable polymers for bone repair and reconstruction, to predict the progress of bone substitute materials and bone tissue engineering scaffolds in future. The literature concerning synthetic biodegradable polymers as bone substitute materials or bone tissue engineering scaffolds was collected and discussed. Aliphatic polyester, polyanhydride, polyurethane and poly (amino acids) were the most extensively studied synthetic biodegradable polymers as bone substitutes and the scaffolds. Each polymer was of good biological safety and biocompatibility, and the degradation products were nontoxic to human body. The mechanical properties and degradation rate of the polymers could be adjusted by the type or number of the monomers and different synthetic methods. Therefore, the polymers with suitable mechanical strength and degradation rate could be produced according to the different requirements for bone grafting. Preliminary studies in vivo showed their favorable capacity for bone repair. The synthetic biodegradable polymers, especially the copolymers, composite materials and those carrying bone growth factors are expected to be the most promising and ideal biomaterials for bone repair and reconstruction.

  11. Biodegradable polymer based theranostic agents for photoacoustic imaging and cancer therapy

    Science.gov (United States)

    Wang, Yan J.; Strohm, Eric M.; Kolios, Michael C.

    2016-03-01

    In this study, multifunctional theranostic agents for photoacoustic (PA), ultrasound (US), fluorescent imaging, and for therapeutic drug delivery were developed and tested. These agents consisted of a shell made from a biodegradable Poly(lactide-co-glycolic acid) (PLGA) polymer, loaded with perfluorohexane (PFH) liquid and gold nanoparticles (GNPs) in the core, and lipophilic carbocyanines fluorescent dye DiD and therapeutic drug Paclitaxel (PAC) in the shell. Their multifunctional capacity was investigated in an in vitro study. The PLGA/PFH/DiD-GNPs particles were synthesized by a double emulsion technique. The average PLGA particle diameter was 560 nm, with 50 nm diameter silica-coated gold nano-spheres in the shell. MCF7 human breast cancer cells were incubated with PLGA/PFH/DiDGNPs for 24 hours. Fluorescent and PA images were recorded using a fluorescent/PA microscope using a 1000 MHz transducer and a 532 nm pulsed laser. For the particle vaporization and drug delivery test, MCF7 cells were incubated with the PLGA/PFH-GNPs-PAC or PLGA/PFH-GNPs particles for 6, 12 and 24 hours. The effects of particle vaporization and drug delivery inside the cells were examined by irradiating the cells with a laser fluence of 100 mJ/cm2, and cell viability quantified using the MTT assay. The PA images of MCF7 cells containing PLGA/PFH/DiD-GNPs were spatially coincident with the fluorescent images, and confirmed particle uptake. After exposure to the PLGA/PFHGNP- PAC for 6, 12 and 24 hours, the cell survival rate was 43%, 38%, and 36% respectively compared with the control group, confirming drug delivery and release inside the cells. Upon vaporization, cell viability decreased to 20%. The particles show potential as imaging agents and drug delivery vehicles.

  12. Poly-γ-Glutamic Acid: Biodegradable Polymer for Potential Protection of Beneficial Viruses

    Directory of Open Access Journals (Sweden)

    Ibrahim R. Khalil

    2016-01-01

    Full Text Available Poly-γ-glutamic acid (γ-PGA is a naturally occurring polymer, which due to its biodegradable, non-toxic and non-immunogenic properties has been used successfully in the food, medical and wastewater industries. A major hurdle in bacteriophage application is the inability of phage to persist for extended periods in the environment due to their susceptibility to environmental factors such as temperature, sunlight, desiccation and irradiation. Thus, the aim of this study was to protect useful phage from the harmful effect of these environmental factors using the γ-PGA biodegradable polymer. In addition, the association between γ-PGA and phage was investigated. Formulated phage (with 1% γ-PGA and non-formulated phage were exposed to 50 °C. A clear difference was noticed as viability of non-formulated phage was reduced to 21% at log10 1.3 PFU/mL, while phage formulated with γ-PGA was 84% at log10 5.2 PFU/mL after 24 h of exposure. In addition, formulated phage remained viable at log10 2.5 PFU/mL even after 24 h of exposure at pH 3 solution. In contrast, non-formulated phages were totally inactivated after the same time of exposure. In addition, non-formulated phages when exposed to UV irradiation died within 10 min. In contrast also phages formulated with 1% γ-PGA had a viability of log10 4.1 PFU/mL at the same exposure time. Microscopy showed a clear interaction between γ-PGA and phages. In conclusion, the results suggest that γ-PGA has an unique protective effect on phage particles.

  13. Effects of Ultraviolet Photon Irradiation on the Dielectric Properties of Biodegradable Polymers

    Science.gov (United States)

    Yamaguchi, Yuya; Uchibori, Nao; Ohki, Yoshimichi

    Three kinds of biodegradable polymers, poly-L-lactic acid (PLLA), polybutylene succinate (PBS), and polybutylene succinate adipate (PBSA), and low-density polyethylene (LDPE) as a reference were irradiated for 30 minutes by ultraviolet (UV) photons from a KrCl excimer lamp. It has become clear that the three biodegradable polymers are far more susceptible to UV photons than LDPE since they absorb UV photons very intensely in the vicinity of the irradiated surface. Space charge distribution profiles show that charge carriers are trapped near the irradiated surface. The conduction current increases by the UV-irradiation in all the biodegradable polymers. Instrumental analyses show that the samples were decomposed by photoinduced oxidation. Furthermore, the absorption spectra indicate the appearance of conjugated double bonds. Such structural changes induced seem to be responsible for the higher conductivity and the charge trapping.

  14. Development and characterization of biodegradable polymer blends - PHBV/PCL irradiated with gamma rays

    International Nuclear Information System (INIS)

    Rosario, F.; Casarin, S.A.; Agnelli, J.A.M.; Souza Junior, O.F. de

    2010-01-01

    This paper presents the results of a study that aimed to develop PHBV biodegradable polymer blends, in a major concentration with PCL, irradiate the pure polymers and blends in two doses of gamma radiation and to analyze the changes in chemical and mechanical properties. The blends used in this study were from natural biodegradable copolymer poly (hydroxybutyrate-valerate) (PHBV) and synthetic biodegradable polymer poly (caprolactone) (PCL 2201) with low molar mass (2,000 g/mol). Several samples were prepared in a co-rotating twin-screw extruder and afterwards, the tensile specimens were injected for the irradiation treatment with 50 kGy to 100 kGy doses and for the mechanical tests. The characterization of the samples before and after the irradiation treatments was performed through scanning electron microscopy (SEM), dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC) and mechanical tensile tests. (author)

  15. Sago Starch-Mixed Low-Density Polyethylene Biodegradable Polymer: Synthesis and Characterization

    Directory of Open Access Journals (Sweden)

    Md Enamul Hoque

    2013-01-01

    Full Text Available This research focuses on synthesis and characterization of sago starch-mixed LDPE biodegradable polymer. Firstly, the effect of variation of starch content on mechanical property (elongation at break and Young’s modulus and biodegradability of the polymer was studied. The LDPE was combined with 10%, 30%, 50%, and 70% of sago for this study. Then how the cross-linking with trimethylolpropane triacrylate (TMPTA and electron beam (EB irradiation influence the mechanical and thermal properties of the polymer was investigated. In the 2nd study, to avoid overwhelming of data LDPE polymer was incorporated with only 50% of starch. The starch content had direct influence on mechanical property and biodegradability of the polymer. The elongation at break decreased with increase of starch content, while Young’s modulus and mass loss (i.e., degradation were found to increase with increase of starch content. Increase of cross-linker (TMPTA and EB doses also resulted in increased Young’s modulus of the polymer. However, both cross-linking and EB irradiation processes rendered lowering of polymer’s melting temperature. In conclusion, starch content and modification processes play significant roles in controlling mechanical, thermal, and degradation properties of the starch-mixed LDPE synthetic polymer, thus providing the opportunity to modulate the polymer properties for tailored applications.

  16. Integrated transformations of plant biomass to valuable chemicals, biodegradable polymers and nanoporous carbons

    Science.gov (United States)

    Kuznetsov, B. N.; Chesnokov, N. V.; Taraban'ko, V. E.; Kuznetsova, S. A.; Petrov, A. V.

    2013-03-01

    Integrated transformations of wood biomass to valuable chemicals and materials are described. They include the main biomass components separation, the conversion of cellulose to glucose, levulinic acid, biodegradable polymers and lignin - to nanoporous carbons. For wood fractionation on pure cellulose and low molecular mass lignin the methods of catalytic oxidation and exploded autohydrolysis are used. The processes of acid-catalysed hydrolysis of cellulose to glucose and levulinic acid were optimized. New methods of biodegradable polymers synthesis from lactone of levulinic acid and nanoporous carbons from lignin were suggested.

  17. Study on the Antimicrobial Properties of Citrate-Based Biodegradable Polymers.

    Science.gov (United States)

    Su, Lee-Chun; Xie, Zhiwei; Zhang, Yi; Nguyen, Kytai Truong; Yang, Jian

    2014-01-01

    Citrate-based polymers possess unique advantages for various biomedical applications since citric acid is a natural metabolism product, which is biocompatible and antimicrobial. In polymer synthesis, citric acid also provides multiple functional groups to control the crosslinking of polymers and active binding sites for further conjugation of biomolecules. Our group recently developed a number of citrate-based polymers for various biomedical applications by taking advantage of their controllable chemical, mechanical, and biological characteristics. In this study, various citric acid derived biodegradable polymers were synthesized and investigated for their physicochemical and antimicrobial properties. Results indicate that citric acid derived polymers reduced bacterial proliferation to different degrees based on their chemical composition. Among the studied polymers, poly(octamethylene citrate) showed ~70-80% suppression to microbe proliferation, owing to its relatively higher ratio of citric acid contents. Crosslinked urethane-doped polyester elastomers and biodegradable photoluminescent polymers also exhibited significant bacteria reduction of ~20 and ~50% for Staphylococcus aureus and Escherichia coli , respectively. Thus, the intrinsic antibacterial properties in citrate-based polymers enable them to inhibit bacteria growth without incorporation of antibiotics, silver nanoparticles, and other traditional bacteria-killing agents suggesting that the citrate-based polymers are unique beneficial materials for wound dressing, tissue engineering, and other potential medical applications where antimicrobial property is desired.

  18. Biodegradable inorganic-organic hybrids of methacrylate star polymers for bone regeneration.

    Science.gov (United States)

    Chung, Justin J; Fujita, Yuki; Li, Siwei; Stevens, Molly M; Kasuga, Toshihiro; Georgiou, Theoni K; Jones, Julian R

    2017-05-01

    Hybrids that are molecular scale co-networks of organic and inorganic components are promising biomaterials, improving the brittleness of bioactive glass and the strength of polymers. Methacrylate polymers have high potential as the organic source for hybrids since they can be produced, through controlled polymerization, with sophisticated polymer architectures that can bond to silicate networks. Previous studies showed the mechanical properties of hybrids can be modified by polymer architecture and molar mass (MM). However, biodegradability is critical if hybrids are to be used as tissue engineering scaffolds, since the templates must be remodelled by host tissue. Degradation by-products have to either completely biodegrade or be excreted by the kidneys. Enzyme, or bio-degradation is preferred to hydrolysis by water uptake as it is expected to give a more controlled degradation rate. Here, branched and star shaped poly(methyl methacrylate-co-3-(trimethoxysilyl)propyl methacrylate) (poly(MMA-co-TMSPMA)) were synthesized with disulphide based dimethacrylate (DSDMA) as a biodegradable branching agent. Biodegradability was confirmed by exposing the copolymers to glutathione, a tripeptide which is known to cleave disulphide bonds. Cleaved parts of the star polymer from the hybrid system were detected after 2weeks of immersion in glutathione solution, and MM was under threshold of kidney filtration. The presence of the branching agent did not reduce the mechanical properties of the hybrids and bone progenitor cells attached on the hybrids in vitro. Incorporation of the DSDMA branching agent has opened more possibilities to design biodegradable methacrylate polymer based hybrids for regenerative medicine. Bioactive glasses can regenerate bone but are brittle. Hybrids can overcome this problem as intimate interactions between glass and polymer creates synergetic properties. Implants have previously been made with synthetic polymers that degrade by water, however, they

  19. Identification of osteoconductive and biodegradable polymers from a combinatorial polymer library.

    Science.gov (United States)

    Brey, Darren M; Chung, Cindy; Hankenson, Kurt D; Garino, Jonathon P; Burdick, Jason A

    2010-05-01

    Combinatorial polymer syntheses are now being utilized to create libraries of materials with potential utility for a wide variety of biomedical applications. We recently developed a library of photopolymerizable and biodegradable poly(beta-amino ester)s (PBAEs) that possess a range of tunable properties. In this study, the PBAE library was assessed for candidate materials that met design criteria (e.g., physical properties such as degradation and mechanical strength and in vitro cell viability and osteoconductive behavior) for scaffolding in mineralized tissue repair. The most promising candidate, A6, was then processed into three-dimensional porous scaffolds and implanted subcutaneously and only presented a mild inflammatory response. The scaffolds were then implanted intramuscularly and into a critical-sized cranial defect either alone or loaded with bone morphogenetic protein-2 (BMP-2). The samples in both locations displayed mineralized tissue formation in the presence of BMP-2, as evident through radiographs, micro-computed tomography, and histology, whereas samples without BMP-2 showed minimal or no mineralized tissue. These results illustrate a process to identify a candidate scaffolding material from a combinatorial polymer library, and specifically for the identification of an osteoconductive scaffold with osteoinductive properties via the inclusion of a growth factor. Copyright 2009 Wiley Periodicals, Inc.

  20. Study on the Antimicrobial Properties of Citrate-Based Biodegradable Polymers

    Directory of Open Access Journals (Sweden)

    Lee-Chun eSu

    2014-07-01

    Full Text Available Citrate-based polymers possess unique advantages for various biomedical applications since citric acid is a natural metabolism product, which is biocompatible and antimicrobial. In polymer synthesis, citric acid also provides multiple functional groups to control the crosslinking of polymers and active binding sites for further conjugation of biomolecules. Our group recently developed a number of citrate-based polymers for various biomedical applications by taking advantage of their controllable chemical, mechanical, and biological characteristics. In this study, various citric acid derived biodegradable polymers were synthesized and investigated for their physicochemical and antimicrobial properties. Results indicate that citric acid derived polymers reduced bacterial proliferation to different degrees based on their chemical composition. Among the studied polymers, poly(octamethylene citrate (POC showed approximately 70-80% suppression to microbe proliferation, owing to its relatively higher ratio of citric acid contents. Crosslinked urethane-doped polyester elastomers (CUPEs and biodegradable photoluminescent polymers (BPLPs also exhibited significant bacteria reduction of ~20% and ~50% for Staphylococcus aureus and Escherichia coli, respectively. Thus, the intrinsic antibacterial properties in citrate-based polymers enable them to inhibit bacteria growth without incorporation of antibiotics, silver nanoparticles, and other traditional bacteria-killing agents suggesting that they are unique beneficial materials for wound dressing, tissue engineering, and other potential medical applications where antimicrobial property is desired.

  1. Biodegradable-Polymer-Blend-Based Surgical Sealant with Body-Temperature-Mediated Adhesion.

    Science.gov (United States)

    Behrens, Adam M; Lee, Nora G; Casey, Brendan J; Srinivasan, Priya; Sikorski, Michael J; Daristotle, John L; Sandler, Anthony D; Kofinas, Peter

    2015-12-22

    The development of practical and efficient surgical sealants has the propensity to improve operational outcomes. A biodegradable polymer blend is fabricated as a nonwoven fiber mat in situ. After direct deposition onto the tissue of interest, the material transitions from a fiber mat to a film. This transition promotes polymer-substrate interfacial interactions leading to improved adhesion and surgical sealant performance. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. [Experimental assessment of biodegradable polyglycolic and polylactic acid polymers for medical use].

    Science.gov (United States)

    Kulakov, A A; Grigor'ian, A S; Arkhipov, A V

    2013-01-01

    Interrelations of biodegradable poliglicolic and polilactic acid polymers in various proportions implanted in standardized bone defects were evaluated in animal model with 40 Wister line rats. During 10 month follow-up period bone capsule surrounded all implants, but timing of bone formation and bone quality varied significantly being optimal in LactoSorb group. Destructive features of polymers were also seen in implant-bone contact area defined as inflammation, fibrous tissue formation and cell dystrophy.

  3. BRANCHED BIODEGRADABLE POLYMERS, A MACROMONOMER, PROCESSES FOR THE PREPARATION OF SAME, AND THEIR USE

    NARCIS (Netherlands)

    Zhong, Zhiyuan; Feijen, Jan; Dijkstra, Pieter J.

    2009-01-01

    The present invention relates to a process for the preparation of branched biodegradable polymers comprising of the steps of: (a) preparing a macromonomer by ring-opening polymerization of at least one cyclic ester, cyclic carbonate, and/or cyclic carboxyanhydride in the presence of a branching

  4. Biolimus-eluting stents with biodegradable polymer versus bare-metal stents in acute myocardial infarction

    DEFF Research Database (Denmark)

    Räber, Lorenz; Kelbæk, Henning; Taniwaki, Masanori

    2014-01-01

    BACKGROUND: This study sought to determine whether the 1-year differences in major adverse cardiac event between a stent eluting biolimus from a biodegradable polymer and bare-metal stents (BMSs) in the COMFORTABLE trial (Comparison of Biolimus Eluted From an Erodible Stent Coating With Bare Metal...

  5. Ring-Opening Polymerization of Lactide to Form a Biodegradable Polymer

    Science.gov (United States)

    Robert, Jennifer L.; Aubrecht, Katherine B.

    2008-01-01

    In this laboratory activity for introductory organic chemistry, students carry out the tin(II) bis(2-ethylhexanoate)/benzyl alcohol mediated ring-opening polymerization of lactide to form the biodegradable polymer polylactide (PLA). As the mechanism of the polymerization is analogous to that of a transesterification reaction, the experiment can be…

  6. Nanofibers extraction from palm mesocarp fiber for biodegradable polymers incorporation

    International Nuclear Information System (INIS)

    Kuana, Vanessa A.; Rodrigues, Vanessa B.; Takahashi, Marcio C.; Campos, Adriana de; Sena Neto, Alfredo R.; Mattoso, Luiz H.C.; Marconcini, Jose M.

    2015-01-01

    The palm mesocarp fibers are residues produced by the palm oil industries. The objective of this paper is to determine an efficient treatment to extract crystal cellulose nanofibers from the palm mesocarp fibers to be incorporated in biodegradable polymeric composites. The fibers were saponified, bleached and analyzed with thermal gravimetric analysis, X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. (author)

  7. Plot of charged nuclear particles in polymers

    International Nuclear Information System (INIS)

    Gallardo H, J.I.L.

    1975-01-01

    Experiments were made in order to obtain particle tracks and fission fragments in polymers. To increase the damage the polymer is attacked chemically with a solution of KOH, NaOH or other chemical agent, whose concentration depends of the polymer to be treated, maintaining a constant temperature during the process. To count the tracks which perforate the film, a spark counter with controlled nitrogen atmosphere was constructed. In the experiments which were made in order to detect particles, films of cellulose nitrate known as xylonite, daicel and red paper were used. For the detection of fission products, cellulose triacetate and cellulose polycarbonate films, known as kodacel and kimfol were used. The particle tracks on the treated films were optically counted with a microscope. They had a diameter between 12 and 30 microns, and when the thickness of the film permitted it the tracks consisted in perforations from one to another side of the film. The obtained results have permitted to have the necessary reproducibility for the realization of quantitative analysis of irradiations which can be applied to neutron dosimetry. (author)

  8. Biodegradable polymers as encapsulation materials for cosmetics and personal care markets.

    Science.gov (United States)

    Ammala, Anne

    2013-04-01

    The topical and transdermal delivery of active cosmetic ingredients requires safe and non-toxic means of reaching the target sites without causing any irritation. Preservation of the active ingredients is also essential during formulation, storage and application of the final product. As many biologically active substances are not stable and sensitive to temperature, pH, light and oxidation, they require encapsulation to protect against unwanted degradation and also to target specific and controlled release of the active substance. The use of biodegradable polymers as encapsulation materials offers several advantages over other carrier materials. Encapsulation of active ingredients using biodegradable polymeric carriers can facilitate increased efficacy and bioavailability and they are also removed from the body via normal metabolic pathways. This article reviews current research on biodegradable polymers as carrier or encapsulation materials for cosmetic and personal care applications. Some of the challenges and limitations are also discussed. Examples of biodegradable polymers reviewed include polysaccharides, poly α-esters, polyalkylcyanoacrylates and polyamidoamine dendrimers. © 2012 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  9. A phenomenological constitutive model for the nonlinear viscoelastic responses of biodegradable polymers

    KAUST Repository

    Khan, Kamran

    2012-11-09

    We formulate a constitutive framework for biodegradable polymers that accounts for nonlinear viscous behavior under regimes with large deformation. The generalized Maxwell model is used to represent the degraded viscoelastic response of a polymer. The large-deformation, time-dependent behavior of viscoelastic solids is described using an Ogden-type hyperviscoelastic model. A deformation-induced degradation mechanism is assumed in which a scalar field depicts the local state of the degradation, which is responsible for the changes in the material\\'s properties. The degradation process introduces another timescale (the intrinsic material clock) and an entropy production mechanism. Examples of the degradation of a polymer under various loading conditions, including creep, relaxation and cyclic loading, are presented. Results from parametric studies to determine the effects of various parameters on the process of degradation are reported. Finally, degradation of an annular cylinder subjected to pressure is also presented to mimic the effects of viscoelastic arterial walls (the outer cylinder) on the degradation response of a biodegradable stent (the inner cylinder). A general contact analysis is performed. As the stiffness of the biodegradable stent decreases, stress reduction in the stented viscoelastic arterial wall is observed. The integration of the proposed constitutive model with finite element software could help a designer to predict the time-dependent response of a biodegradable stent exhibiting finite deformation and under complex mechanical loading conditions. © 2012 Springer-Verlag Wien.

  10. Computed tomography of Lipiodol-loaded biodegradable pasty polymer for implant visualization.

    Science.gov (United States)

    Sosna, Jacob; Havivi, Ehud; Khan, Wahid; Appelbaum, Liat; Nyska, Abraham; Domb, Abraham J

    2014-01-01

    Targeted delivery of drug-loaded implants for regional drug therapy has become an important approach to therapy. Simple and reproducible imaging methodologies to evaluate the implant noninvasively are needed. The goal of this work was to noninvasively evaluate the visibility, shape and degradation of a biodegradable implant containing Lipiodol (an X-ray contrast medium) by computed tomography (CT). For in vitro evaluation, Lipiodol was incorporated in poly(sebacic-co-ricinoleic acid) [P(SA:RA)], a biodegradable injectable pasty polymer, and CT visibility was assessed. For ex vivo evaluation, bovine liver was injected with the polymer-loaded Lipiodol; for in vivo evaluation rats were injected subcutaneously with Lipiodol in polymer and CT was performed. We show that polymer diameter at CT correlates with implant weight and pathological measurements. Polymer formulation containing 5% Lipiodol was visible on CT in vitro. Ex vivo tests showed a round polymer deposit at the injection site compared with free dispersion of Lipiodol alone. Correlation between implant size at CT scan and surgery at 48 h was R(2)  = 0.78. Average CT diameter at 9 days was 14.2 ± 2.8 mm in rats injected with Lipiodol in the polymer formulation, as compared with 7.3 ± 1.1 mm in controls. After 9 days, the implant degraded into several zones containing inflammatory cells seen on CT as areas with increased heterogeneity. In conclusion, Lipiodol incorporated in P(SA:RA) is visible on CT, and polymer degradation can potentially be monitored noninvasively. This method can be widely applied to follow changes in biodegradable implants. Copyright © 2014 John Wiley & Sons, Ltd.

  11. Gene silencing activity of siRNA polyplexes based on biodegradable polymers.

    Science.gov (United States)

    Varkouhi, Amir K; Lammers, Twan; Schiffelers, Raymond M; van Steenbergen, Mies J; Hennink, Wim E; Storm, Gert

    2011-04-01

    Cationic polymers are used as non-viral vectors for nucleic acid delivery. In this study, two biodegradable cationic polymers were evaluated for the purpose of siRNA delivery: pHPMA-MPPM (poly((2-hydroxypropyl) methacrylamide 1-methyl-2-piperidine methanol)) and TMC (O-methyl-free N,N,N-trimethylated chitosan). The silencing activity and the cellular cytotoxicity of polyplexes based on these biodegradable polymers were compared with those based on non-biodegradable pDMAEMA (poly(2-dimethylamino)ethyl methacrylate) and PEI (polyethylenimine) and with the regularly used lipidic transfection agent Lipofectamine. To promote endosomal escape, either the endosomolytic peptide diINF-7 was added to the formulations or photochemical internalization (PCI) was applied. Incubation of H1299 human lung cancer cells expressing firefly luciferase with polyplexes based on pHPMA-MPPM and TMC showed 30-40% silencing efficiency. This silencing activity was equal to or better than that obtained with the standard transfectants. Under all experimental conditions tested, the cytotoxicity of the biodegradable polymers was low. The application of PCI, as well as the addition of the diINF-7 peptide to the formulations increased their silencing activity up to 70-80%. This demonstrates that pHPMA-MPPM- and TMC-based polyplexes benefit substantially from endosomal escape enhancement. Importantly, the polyplexes retained their silencing activity in the presence of serum, and they showed low cytotoxicity. These biodegradable vectors are therefore attractive systems for further in vivo evaluations. Copyright © 2010 Elsevier B.V. All rights reserved.

  12. Novel pH-sensitive biodegradable polymeric drug delivery systems based on ketal polymers.

    Science.gov (United States)

    Chen, Daquan; Wang, Hongbo

    2014-01-01

    This article reviews the recent developments on novel pH-sensitive ketal-based biodegradable polymeric drug delivery systems. Due to the degradation of ketal derivatives, neutral alcohols and ketones, ketal derivatives can be used to fabricate pH-degradable polymer with pH-degradable ketal linkages in new drug delivery systems by avoiding inflammatory problems. Due to the novelty of ketal polymers, there were few reports about ketal polymers. The review starts with a brief introduction to the pH-sensitive drug delivery system, followed by the structure, preparation and characterization techniques of ketal polymers. Thereafter, the promising applications in various diseases in relation to micro/nano drug carriers based on ketal polymers are summarized and discussed.

  13. Biodegradation of Secondary Phase Particles in Magnesium Alloys: A Critical Review

    Energy Technology Data Exchange (ETDEWEB)

    Kannan, M. Bobby [James Cook University, Townsville (Australia)

    2016-04-15

    Magnesium alloys have been extensively studied in recent years for potential biodegradable implant applications. A great deal of work has been done on the evaluation of the corrosion behaviour of magnesium alloys under in vitro and in vivo conditions. However, magnesium alloys, in general, contain secondary phase particles distributed in the matrix and/or along the grain boundaries. Owing to their difference in chemistry in comparison with magnesium matrix, these particles may exhibit different corrosion behaviour. It is essential to understand the corrosion behaviour of secondary phase particles in magnesium alloys in physiological conditions for implant applications. This paper critically reviews the biodegradation behaviour of secondary phase particles in magnesium alloys.

  14. Nanoscale Particle Motion in Attractive Polymer Nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Senses, Erkan; Narayanan, Suresh; Mao, Yimin; Faraone, Antonio

    2017-12-01

    Using x-ray photon correlation spectroscopy, we examined slow nanoscale motion of silica nanoparticles individually dispersed in entangled poly (ethylene oxide) melt at particle volume fractions up to 42 %. The nanoparticles, therefore, serve as both fillers for the resulting attractive polymer nanocomposites and probes for the network dynamics therein. The results show that the particle relaxation closely follows the mechanical reinforcement in the nanocomposites only at the intermediate concentrations below the critical value for the chain confinement. Quite unexpectedly, the relaxation time of the particles does not further slowdown at higher volume fractions- when all chains are practically on the nanoparticle interface- and decouples from the elastic modulus of the nanocomposites that further increases orders of magnitude.

  15. Nanoscale Particle Motion in Attractive Polymer Nanocomposites

    Science.gov (United States)

    Senses, Erkan; Narayanan, Suresh; Mao, Yimin; Faraone, Antonio

    2017-12-01

    Using x-ray photon correlation spectroscopy, we examined the slow nanoscale motion of silica nanoparticles individually dispersed in an entangled poly (ethylene oxide) melt at particle volume fractions up to 42%. The nanoparticles, therefore, serve as both fillers for the resulting attractive polymer nanocomposites and probes for the network dynamics therein. The results show that the particle relaxation closely follows the mechanical reinforcement in the nanocomposites only at the intermediate concentrations below the critical value for the chain confinement. Quite unexpectedly, the relaxation time of the particles does not further slow down at higher volume fractions—when all chains are practically on the nanoparticle interface—and decouples from the elastic modulus of the nanocomposites that further increases orders of magnitude.

  16. Comparison of Durable-Polymer Zotarolimus-Eluting and Biodegradable-Polymer Biolimus-Eluting Coronary Stents in Patients With Coronary Artery Disease

    DEFF Research Database (Denmark)

    Raungaard, Bent; Christiansen, Evald H; Bøtker, Hans Erik

    2017-01-01

    OBJECTIVES: The authors sought to compare the safety and efficacy of the biocompatible durable-polymer zotarolimus-eluting stent with the biodegradable-polymer biolimus-eluting stent in unselected coronary patients. BACKGROUND: Biodegradable-polymer biolimus-eluting stents are superior to first......:1) to receive either the zotarolimus-eluting (1,502 patients) or the biolimus-eluting (1,497 patients) stent. At 3-year follow-up, MACE occurred in 128 (8.6%) patients assigned to the durable-polymer zotarolimus-eluting stent and in 144 (9.6%) assigned to the biodegradable-polymer biolimus-eluting stent (p = 0...... to the durable-polymer zotarolimus-eluting stent and in 10 (0.7%) assigned to the biodegradable-polymer biolimus-eluting stent (p = 0.33). CONCLUSIONS: At 3-year follow-up, the durable-polymer zotarolimus-eluting stent and the biodegradable-polymer biolimus-eluting stent were similar in clinical outcome...

  17. Study of thermal and mechanical properties of nanocomposites, synthesized from the organoclays and biodegradable polymers

    International Nuclear Information System (INIS)

    Botelho, K.T.; Wiebeck, H.; Valenzuela-Diaz, F.R.

    2011-01-01

    The smectitic clays (MMT-Na + ) have a broad range of industrial applications. The smectitic clays which the exchangeable cation sodium predominates have much more applications in this class of mineral. The sodium smectitic clays are hydrophilic in character with a high water Foster swelling. For uses in organic medium, where a high hydrophobicity and swelling are necessary, we must transform them in the organoclay form. This is accomplished by the cation exchange reaction of the sodium smectitic clay water dispersion with quaternary ammonium salts. In this paper, it was used the smectitic clays (MMT-Na + ) from Argentina with CEC of 120meq/100g and swelling in water close to 20mL. Its modification was made using five quaternary ammonium salts. We characterize both sodium smectitic clay and the organoclay by X-ray diffraction (XRD) providing that occurred a basal expansion at the MMT-Na + for the five quaternary ammonium salts, Foster swelling and Infrared Spectra. After the synthesis, was done extrusion the two biodegradable plastics with the aim to incorporate the organoclay in these polymers. For characterization the biodegradable polymers, the proper choice is the thermal analysis and the mechanical test. Such analysis was effectuated in to pure plastic and the polymers nanocomposite, to proven of the resistance to the high temperature and the increased the mechanical properties of the modificated polymers when compared with the pure biodegradable plastics. (author)

  18. Sustained Release of Antibacterial Lipopeptides from Biodegradable Polymers against Oral Pathogens.

    Science.gov (United States)

    Eckhard, Lea H; Houri-Haddad, Yael; Sol, Asaf; Zeharia, Rotem; Shai, Yechiel; Beyth, Shaul; Domb, Abraham J; Bachrach, Gilad; Beyth, Nurit

    2016-01-01

    The development of antibacterial drugs to overcome various pathogenic species, which inhabit the oral cavity, faces several challenges, such as salivary flow and enzymatic activity that restrict dosage retention. Owing to their amphipathic nature, antimicrobial peptides (AMPs) serve as the first line of defense of the innate immune system. The ability to synthesize different types of AMPs enables exploitation of their advantages as alternatives to antibiotics. Sustained release of AMPs incorporated in biodegradable polymers can be advantageous in maintaining high levels of the peptides. In this study, four potent ultra-short lipopeptides, conjugated to an aliphatic acid chain (16C) were incorporated in two different biodegradable polymers: poly (lactic acid co castor oil) (PLACO) and ricinoleic acid-based poly (ester-anhydride) (P(SA-RA)) for sustained release. The lipopeptide and polymer formulations were tested for antibacterial activity during one week, by turbidometric measurements of bacterial outgrowth, anti-biofilm activity by live/dead staining, biocompatibility by hemolysis and XTT colorimetric assays, mode of action by fluorescence-activated cell sorting (FACS) and release profile by a fluorometric assay. The results show that an antibacterial and anti-biofilm effect, as well as membrane disruption, can be achieved by the use of a formulation of lipopeptide incorporated in biodegradable polymer.

  19. Performance of Biodegradable Polymers used in Mechanically Loaded Implants

    DEFF Research Database (Denmark)

    Andersen, Lonnie Ulrich

    predisposing for early dislocation have not been completely established, making it difficult to take successful preventative measures. The objective of this PhD thesis was to design an implantable, biodegradable device to guard against these dislocations. The hip dislocation preventer should allow for easy...... to be oriented in a 45° angle to the direction of deformation. From the model the initial strain region was predicted to lie between 35-40%, and the tensile force that the fabric can withstand, without going into plastic deformation was between 2000-5000 N. From the analysis and the material tests it was found...

  20. Investigating the crystal growth behavior of biodegradable polymer blend thin films using in situ atomic force microscopy

    CSIR Research Space (South Africa)

    Malwela, T

    2014-01-01

    Full Text Available This article reports the crystal growth behavior of biodegradable polylactide (PLA)/poly[(butylene succinate)-co-adipate] (PBSA) blend thin films using atomic force microscopy (AFM). Currently, polymer thin films have received increased research...

  1. Physical and Degradable Properties of Mulching Films Prepared from Natural Fibers and Biodegradable Polymers

    Directory of Open Access Journals (Sweden)

    Zhijian Tan

    2016-05-01

    Full Text Available The use of plastic film in agriculture has the serious drawback of producing vast quantities of waste. In this work, films were prepared from natural fibers and biodegradable polymers as potential substitutes for the conventional non-biodegradable plastic film used as mulching material in agricultural production. The physical properties (e.g., mechanical properties, heat preservation, water permeability, and photopermeability and degradation characteristics (evaluated by micro-organic culture testing and soil burial testing of the films were studied in both laboratory and field tests. The experimental results indicated that these fiber/polymer films exhibited favorable physical properties that were sufficient for use in mulching film applications. Moreover, the degradation degree of the three tested films decreased in the following order: fiber/starch (ST film > fiber/poly(vinyl alcohol (PVA film > fiber/polyacrylate (PA film. The fiber/starch and fiber/PVA films were made from completely biodegradable materials and demonstrated the potential to substitute non-biodegradable films.

  2. Poly(dopamine) coating to biodegradable polymers for bone tissue engineering.

    Science.gov (United States)

    Tsai, Wei-Bor; Chen, Wen-Tung; Chien, Hsiu-Wen; Kuo, Wei-Hsuan; Wang, Meng-Jiy

    2014-02-01

    In this study, a technique based on poly(dopamine) deposition to promote cell adhesion was investigated for the application in bone tissue engineering. The adhesion and proliferation of rat osteoblasts were evaluated on poly(dopamine)-coated biodegradable polymer films, such as polycaprolactone, poly(l-lactide) and poly(lactic-co-glycolic acid), which are commonly used biodegradable polymers in tissue engineering. Cell adhesion was significantly increased to a plateau by merely 15 s of dopamine incubation, 2.2-4.0-folds of increase compared to the corresponding untreated substrates. Cell proliferation was also greatly enhanced by poly(dopamine) deposition, indicated by shortened cell doubling time. Mineralization was also increased on the poly(dopamine)-deposited surfaces. The potential of poly(dopamine) deposition in bone tissue engineering is demonstrated in this study.

  3. Biomedical applications of synthetic, biodegradable polymers for the development of anti-infective strategies.

    Science.gov (United States)

    Bertesteanu, Serban; Chifiriuc, Mariana Carmen; Grumezescu, Alexandru Mihai; Printza, Atnanasia G; Marie-Paule, Thill; Grumezescu, Valentina; Mihaela, Vlad; Lazar, Veronica; Grigore, Raluca

    2014-01-01

    The emergence of antibiotic resistance in microbial strains is representing one of the major threats to public health worldwide, due to the decreased or total cancelling of the available antibiotics effectiveness, correlated with the slow development of novel antibiotics. Due to their excellent biodegradability and biocompatibility, the synthetic polymers could find a lot of biomedical applications, such as the development of biomaterials with optimized properties and of drug delivery systems. This review is focusing on the applications of synthetic, biodegradable polymers for the improvement of antiinfective therapeutic and prophylactic agents (i.e., antimicrobial and anti-inflammatory agents and vaccines) activity, as well as for the design of biomaterials with increased biocompatibility and resistance to microbial colonization.

  4. The use of biodegradable polymers for the stabilization of copper ...

    Indian Academy of Sciences (India)

    2017-08-03

    Aug 3, 2017 ... However, agglomerated copper nanoparticles were obtained by this chemical reduction method. Hence, the effects of three polymers of polyvinyl pyrrolidone, polyethylene glycol (PEG) and starch as stabilizers on the size and size distribution of Cu nanoparticles were investigated. According to the results,.

  5. Study of in vitro degradation of biodegradable polymer based thin ...

    African Journals Online (AJOL)

    GREGORY

    2011-12-16

    Dec 16, 2011 ... Science and Biomedical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor, Malaysia. Accepted 7 November, 2011 .... polymers approved by the US Food and Drug. Administration (FDA) for certain ... equation is applicable when the extent of reaction is slow or before the specimen ...

  6. A model for hydrolytic degradation and erosion of biodegradable polymers.

    Science.gov (United States)

    Sevim, Kevser; Pan, Jingzhe

    2018-01-15

    For aliphatic polyesters such as PLAs and PGAs, there is a strong interplay between the hydrolytic degradation and erosion - degradation leads to a critically low molecular weight at which erosion starts. This paper considers the underlying physical and chemical processes of hydrolytic degradation and erosion. Several kinetic mechanisms are incorporated into a mathematical model in an attempt to explain different behaviours of mass loss observed in experiments. In the combined model, autocatalytic hydrolysis, oligomer production and their diffusion are considered together with surface and interior erosion using a set of differential equations and Monte Carlo technique. Oligomer and drug diffusion are modelled using Fick's law with the diffusion coefficients dependent on porosity. The porosity is due to the formation of cavities which are a result of polymer erosion. The model can follow mass loss and drug release up to 100%, which cannot be explained using a simple reaction-diffusion. The model is applied to two case studies from the literature to demonstrate its validity. The case studies show that a critical molecular weight for the onset of polymer erosion and an incubation period for the polymer dissolution are two critical factors that need to be considered when predicting mass loss and drug release. In order to design bioresorbable implants, it is important to have a mathematical model to predict polymer degradation and corresponding drug release. However, very different behaviours of polymer degradation have been observed and there is no single model that can capture all these behaviours. For the first time, the model presented in this paper is capable of capture all these observed behaviours by switching on and off different underlying mechanisms. Unlike the existing reaction-diffusion models, the model presented here can follow the degradation and drug release all the way to the full disappearance of an implant. Crown Copyright © 2017. Published by

  7. Measuring the Biodegradability of Plastic Polymers in Olive-Mill Waste Compost with an Experimental Apparatus

    Directory of Open Access Journals (Sweden)

    Francesco Castellani

    2016-01-01

    Full Text Available The use of biodegradable polymers is spreading in agriculture to replace those materials derived from petroleum, thus reducing the environmental concerns. However, to issue a significant assessment, biodegradation rate must be measured in case-specific standardized conditions. In accordance with ISO 14855-1, we designed and used an experimental apparatus to evaluate the biodegradation rate of three biopolymers based on renewable resources, two poly(ε-caprolactone (PCL composites, and a compatibilized polylactic acid and polybutyrate (PLA/PBAT blend. Biodegradation tests were carried out under composting condition using mature olive-mill waste (OMW compost as inoculum. Carbon dioxide emissions were automatically recorded by infrared gas detectors and also trapped in saturated Ba(OH2 solution and evaluated via a standard titration method to check the results. Some of the samples reached more than 80% biodegradation in less than 20 days. Both the experimental apparatus and the OMW compost showed to be suitable for the cases studied.

  8. Efficacy and safety of biodegradable polymer biolimus-eluting stents versus durable polymer drug-eluting stents: a meta-analysis.

    Science.gov (United States)

    Ye, Yicong; Xie, Hongzhi; Zeng, Yong; Zhao, Xiliang; Tian, Zhuang; Zhang, Shuyang

    2013-01-01

    Drug-eluting stents (DES) with biodegradable polymers have been developed to address the risk of thrombosis associated with first-generation DES. We aimed to determine the efficacy and safety of biodegradable polymer biolimus-eluting stents (BES) versus durable polymer DES. Systematic database searches of MEDLINE (1950 to June 2013), EMBASE (1966 to June 2013), the Cochrane Central Register of Controlled Trials (Issue 6 of 12, June 2013), and a review of related literature were conducted. All randomized controlled trials comparing biodegradable polymer BES versus durable polymer DES were included. Eight randomized controlled trials investigating 11,015 patients undergoing percutaneous coronary interventions were included in the meta-analysis. The risk of major adverse cardiac events did not differ significantly between the patients treated with the biodegradable polymer BES and the durable polymer DES (Relative risk [RR], 0.970; 95% CI, 0.848-1.111; p = 0.662). However, biodegradable polymer BES was associated with reduced risk of very late ST compared with the durable polymer DES, while the risk of early or late ST was similar (RR for early or late ST, 1.167; 95% CI 0.755-1.802; p = 0.487; RR 0.273; 95% CI 0.115-0.652; p = 0.003; p for interaction = 0.003). In this meta-analysis of randomized controlled trials, treatments with biodegradable polymer BES did not significantly reduce the risk of major adverse cardiac events, but demonstrated a significantly lower risk of very late ST when compared to durable polymer DES. This conclusion requires confirmation by further studies with long-term follow-up. http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42013004364#.UnM2lfmsj6J.

  9. Efficacy and safety of biodegradable polymer biolimus-eluting stents versus durable polymer drug-eluting stents: a meta-analysis.

    Directory of Open Access Journals (Sweden)

    Yicong Ye

    Full Text Available BACKGROUNDS: Drug-eluting stents (DES with biodegradable polymers have been developed to address the risk of thrombosis associated with first-generation DES. We aimed to determine the efficacy and safety of biodegradable polymer biolimus-eluting stents (BES versus durable polymer DES. METHODS: Systematic database searches of MEDLINE (1950 to June 2013, EMBASE (1966 to June 2013, the Cochrane Central Register of Controlled Trials (Issue 6 of 12, June 2013, and a review of related literature were conducted. All randomized controlled trials comparing biodegradable polymer BES versus durable polymer DES were included. RESULTS: Eight randomized controlled trials investigating 11,015 patients undergoing percutaneous coronary interventions were included in the meta-analysis. The risk of major adverse cardiac events did not differ significantly between the patients treated with the biodegradable polymer BES and the durable polymer DES (Relative risk [RR], 0.970; 95% CI, 0.848-1.111; p = 0.662. However, biodegradable polymer BES was associated with reduced risk of very late ST compared with the durable polymer DES, while the risk of early or late ST was similar (RR for early or late ST, 1.167; 95% CI 0.755-1.802; p = 0.487; RR 0.273; 95% CI 0.115-0.652; p = 0.003; p for interaction = 0.003. CONCLUSIONS: In this meta-analysis of randomized controlled trials, treatments with biodegradable polymer BES did not significantly reduce the risk of major adverse cardiac events, but demonstrated a significantly lower risk of very late ST when compared to durable polymer DES. This conclusion requires confirmation by further studies with long-term follow-up. PROSPERO REGISTER NUMBER: http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42013004364#.UnM2lfmsj6J.

  10. Obtaining and characterization of a biodegradable polymer starting from the tapioca starch

    International Nuclear Information System (INIS)

    Ruiz Aviles, Gladys

    2006-01-01

    This study focuses on the preparation of tapioca starch biodegradable polymer, processed by blends of starch modified with glycerin and water as plasticizers, by using roll mill and a single-screw extruder in the process. During extrusion, there is a series of variables to control namely: the barrel temperature profile, screw torque and screw rotation speed. Tensile test, differential scanning calorimetric (DSC), thermogravimetric analysis (TGA), Fourier transformer infrared spectroscopy (FTIR) and morphology were used in the process

  11. Poly(trimethylene carbonate)-based polymers engineered for biodegradable functional biomaterials.

    Science.gov (United States)

    Fukushima, K

    2016-01-01

    Aliphatic polycarbonates have drawn attention as biodegradable polymers that can be applied to a broad range of resorbable medical devices. In particular, poly(trimethylene carbonate) (PTMC), its copolymers, and its derivatives are currently studied due to their unique degradation characteristics that are different from those of aliphatic polyesters. Furthermore, their flexible and hydrophobic nature has driven the application of PTMC-based polymers to soft tissue regeneration and drug delivery. This review presents the diverse applications and functionalization strategies of PTMC-based materials in relation to recent advances in medical technologies and their subsequent needs in clinical settings.

  12. Morphology and transport in biodegradable polymer compositions based on poly(3-hydroxybutyrate) and polyamide 54C

    Energy Technology Data Exchange (ETDEWEB)

    Zhul' kina, A. L.; Ivantsova, E. L.; Filatova, A. G.; Kosenko, R. Yu.; Gumargalieva, K. Z.; Iordanskii, A. L., E-mail: iordan@chph.ras.ru [Russian Academy of Sciences, Semenov Institute of Chemical Physics (Russian Federation)

    2009-05-15

    Complex investigation of the equilibrium sorption of water, diffusive transport of antiseptic, and morphology of mixed compositions based on polyoxybutirate and polyamide resin 54C has been performed to develop and analyze new biodegradable polymer compositions for controlled release of medicinal substances. Samples of mixtures were prepared by two methods: pressing under pressure and solvent evaporation from a polymer solution. The samples were compared and their morphology was analyzed by scanning electron microscopy. It is shown that the component ratio in the obtained mixtures affects their morphological, transport, and sorption characteristics.

  13. Morphology and transport in biodegradable polymer compositions based on poly(3-hydroxybutyrate) and polyamide 54C

    International Nuclear Information System (INIS)

    Zhul'kina, A. L.; Ivantsova, E. L.; Filatova, A. G.; Kosenko, R. Yu.; Gumargalieva, K. Z.; Iordanskii, A. L.

    2009-01-01

    Complex investigation of the equilibrium sorption of water, diffusive transport of antiseptic, and morphology of mixed compositions based on polyoxybutirate and polyamide resin 54C has been performed to develop and analyze new biodegradable polymer compositions for controlled release of medicinal substances. Samples of mixtures were prepared by two methods: pressing under pressure and solvent evaporation from a polymer solution. The samples were compared and their morphology was analyzed by scanning electron microscopy. It is shown that the component ratio in the obtained mixtures affects their morphological, transport, and sorption characteristics.

  14. A study on thermal properties of biodegradable polymers using photothermal methods

    Science.gov (United States)

    Siqueira, A. P. L.; Poley, L. H.; Sanchez, R.; da Silva, M. G.; Vargas, H.

    2005-06-01

    In this work is reported the use of photothermal techniques applied to the thermal characterization of biodegradable polymers of Polyhydroxyalkanoates (PHAs) family. This is a family of polymer produced by bacteria using renewable resources. It exhibits thermoplastic properties and therefore it can be an alternative product for engineering plastics, being also applied as packages for food industry and fruits. Thermal diffusivities were determined using the open photoacoustic cell (OPC) configuration. Specific heat capacity measurements were performed monitoring temperature of the samples under white light illumination against time. Typical values obtained for the thermal properties are in good agreement with those found in the literature for other polymers. Due to the incorporation of hydroxyvalerate in the monomer structure, the thermal diffusivity and thermal conductivity increase reaching a saturation value, otherwise the specific thermal capacity decreases as the concentration of the hydroxyvalerate (HV) increases. These results can be explained by polymers internal structure and are allowing new applications of these materials.

  15. Development of partially biodegradable foams from PP/HMSPP blends with natural and synthetic polymers

    International Nuclear Information System (INIS)

    Cardoso, Elizabeth Carvalho Leite

    2014-01-01

    Polymers are used in various application and in different industrial areas providing enormous quantities of wastes in environment. Among diverse components of residues in landfills are polymeric materials, including Polypropylene, which contribute with 20 to 30% of total volume of solid residues. As polymeric materials are immune to microbial degradation, they remain in soil and in landfills as a semi-permanent residue. Environmental concerning in litter reduction is being directed to renewable polymers development for manufacturing of polymeric foams. Foamed polymers are considered future materials, with a wide range of applications; high density structural foams are specially used in civil construction, in replacement of metal, woods and concrete with a final purpose of reducing materials costs. At present development, it was possible the incorporation of PP/HMSPP polymeric matrix blends with sugarcane bagasse, PHB and PLA, in structural foams production. Thermal degradation at 100, 120 and 160 deg C temperatures was not enough to induce biodegradability. Gamma irradiation degradation, at 50, 100, 200 and 500 kGy showed effective for biodegradability induction. Irradiated bagasse blends suffered surface erosion, in favor of water uptake and consequently, a higher biodegradation in bulk structure. (author)

  16. Biodegradable Polymers Influence the Effect of Atorvastatin on Human Coronary Artery Cells.

    Science.gov (United States)

    Strohbach, Anne; Begunk, Robert; Petersen, Svea; Felix, Stephan B; Sternberg, Katrin; Busch, Raila

    2016-01-22

    Drug-eluting stents (DES) have reduced in-stent-restenosis drastically. Yet, the stent surface material directly interacts with cascades of biological processes leading to an activation of cellular defense mechanisms. To prevent adverse clinical implications, to date almost every patient with a coronary artery disease is treated with statins. Besides their clinical benefit, statins exert a number of pleiotropic effects on endothelial cells (ECs). Since maintenance of EC function and reduction of uncontrolled smooth muscle cell (SMC) proliferation represents a challenge for new generation DES, we investigated the effect of atorvastatin (ATOR) on human coronary artery cells grown on biodegradable polymers. Our results show a cell type-dependent effect of ATOR on ECs and SMCs. We observed polymer-dependent changes in IC50 values and an altered ATOR-uptake leading to an attenuation of statin-mediated effects on SMC growth. We conclude that the selected biodegradable polymers negatively influence the anti-proliferative effect of ATOR on SMCs. Hence, the process of developing new polymers for DES coating should involve the characterization of material-related changes in mechanisms of drug actions.

  17. Shape-memory effect by specific biodegradable polymer blending for biomedical applications.

    Science.gov (United States)

    Cha, Kook Jin; Lih, Eugene; Choi, Jiyeon; Joung, Yoon Ki; Ahn, Dong Jun; Han, Dong Keun

    2014-05-01

    Specific biodegradable polymers having shape-memory properties through "polymer-blend" method are investigated and their shape-switching in body temperature (37 °C) is characterized. Poly(L-lactide-co-caprolactone) (PLCL) and poly(L-lactide-co-glycolide) (PLGA) are dissolved in chloroform and the films of several blending ratios of PLCL/PLGA are prepared by solvent casting. The shape-memory properties of films are also examined using dynamic mechanical analysis (DMA). Among the blending ratios, the PLCL50/PLGA50 film shows good performance of shape-fixity and shape-recovery based on glass transition temperature. It displays that the degree of shape recovery is 100% at 37 °C and the shape recovery proceeds within only 15 s. In vitro biocompatibility studies are shown to have good blood compatibility and cytocompatibility for the PLCL50/PLGA50 films. It is expected that this blended biodegradable polymer can be potentially used as a material for blood-contacting medical devices such as a self-expended vascular polymer stents and vascular closure devices in biomedical applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Zotarolimus-eluting durable-polymer-coated stent versus a biolimus-eluting biodegradable-polymer-coated stent in unselected patients undergoing percutaneous coronary intervention (SORT OUT VI)

    DEFF Research Database (Denmark)

    Raungaard, Bent; Jensen, Lisette Okkels; Tilsted, Hans-Henrik

    2015-01-01

    -polymer zotarolimus-eluting stent or the biodegradable-polymer biolimus-eluting stent. The primary endpoint was a composite of safety (cardiac death and myocardial infarction not clearly attributable to a non-target lesion) and efficacy (target-lesion revascularisation) at 12 months, analysed by intention to treat...

  19. Continuous production of functionalized polymer particles employing the phase separation in polymer blend films.

    Science.gov (United States)

    Park, ChooJin; Hyun, Dong Choon; Lim, Min-Cheol; Kim, Su-Jeong; Kim, Young-Rok; Paik, Hyun-Jong; Jeong, Unyong

    2011-08-17

    This study reports a continuous prepartion of spherical or hemispherical polymer particles simply utilizing the phase separation in polymer blend films during the coating process. We took an advantage of the strong phase separation between a water-soluble crystalline polymer as a matrix and hydrophobic polymers as minor components. We demonstrated the prepartion of water-soluble polystyrene (PS) particles, nitrilotriacetic acid (NTA)-functionalized PS particles for protein separation, and semiconducting poly(3-hexylthiophene) (P3HT) particles. The sizes of the particles could be controlled by adjusting the film thickness and weight fraction of the minor component polymers in the blend film. It provides a simple facile way to prepare polymer particles in a continous process. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Biodegradable polyester-based shape memory polymers: Concepts of (supramolecular architecturing

    Directory of Open Access Journals (Sweden)

    J. Karger-Kocsis

    2014-06-01

    Full Text Available Shape memory polymers (SMPs are capable of memorizing one or more temporary shapes and recovering to the permanent shape upon an external stimulus that is usually heat. Biodegradable polymers are an emerging family within the SMPs. This minireview delivers an overlook on actual concepts of molecular and supramolecular architectures which are followed to tailor the shape memory (SM properties of biodegradable polyesters. Because the underlying switching mechanisms of SM actions is either related to the glass transition (Tg or melting temperatures (Tm, the related SMPs are classified as Tg- or Tm-activated ones. For fixing of the permanent shape various physical and chemical networks serve, which were also introduced and discussed. Beside of the structure developments in one-way, also those in two-way SM polyesters were considered. Adjustment of the switching temperature to that of the human body, acceleration of the shape recovery, enhancement of the recovery stress, controlled degradation, and recycling aspects were concluded as main targets for the future development of SM systems with biodegradable polyesters.

  1. Development of biodegradable polymer based tamoxifen citrate loaded nanoparticles and effect of some manufacturing process parameters on them: a physicochemical and in-vitro evaluation

    Directory of Open Access Journals (Sweden)

    Basudev Sahana

    2010-08-01

    Full Text Available Basudev Sahana, Kousik Santra, Sumit Basu, Biswajit MukherjeeDepartment of Pharmaceutical Technology, Jadavpur University, Kolkata, IndiaAbstract: The aim of the present study was to develop nanoparticles of tamoxifen citrate, a non-steroidal antiestrogenic drug used for the treatment of breast cancer. Biodegradable poly (D, L- lactide-co-glycolide-85:15 (PLGA was used to develop nanoparticles of tamoxifen citrate by multiple emulsification (w/o/w and solvent evaporation technique. Drug-polymer ratio, polyvinyl alcohol concentrations, and homogenizing speeds were varied at different stages of preparation to optimize the desired size and release profile of drug. The characterization of particle morphology and shape was performed by field emission scanning electron microscope (FE-SEM and particle size distribution patterns were studied by direct light scattering method using zeta sizer. In vitro drug release study showed that release profile of tamoxifen from biodegradable nanoparticles varied due to the change in speed of centrifugation for separation. Drug loading efficiency varied from 18.60% to 71.98%. The FE-SEM study showed that biodegradable nanoparticles were smooth and spherical in shape. The stability studies of tamoxifen citrate in the experimental nanoparticles showed the structural integrity of tamoxifen citrate in PLGA nanoparticles up to 60°C in the tested temperatures. Nanoparticles containing tamoxifen citrate could be useful for the controlled delivery of the drug for a prolonged period.Keywords: biodegradable, nanoparticles, PLGA, stability, tamoxifen citrate

  2. Biodegradable-Polymer Biolimus-Eluting Stents versus Durable-Polymer Everolimus-Eluting Stents at One-Year Follow-Up: A Registry-Based Cohort Study.

    Science.gov (United States)

    Parsa, Ehsan; Saroukhani, Sepideh; Majlessi, Fereshteh; Poorhosseini, Hamidreza; Lofti-Tokaldany, Masoumeh; Jalali, Arash; Salarifar, Mojtaba; Nematipour, Ebrahim; Alidoosti, Mohammad; Aghajani, Hassan; Amirzadegan, Alireza; Kassaian, Seyed Ebrahim

    2016-04-01

    We compared outcomes of percutaneous coronary intervention patients who received biodegradable-polymer biolimus-eluting stents with those who received durable-polymer everolimus-eluting stents. At Tehran Heart Center, we performed a retrospective analysis of the data from January 2007 through December 2011 on 3,270 consecutive patients with coronary artery disease who underwent percutaneous coronary intervention with the biodegradable-polymer biolimus-eluting stent or the durable-polymer everolimus-eluting stent. We excluded patients with histories of coronary artery bypass grafting or percutaneous coronary intervention, acute ST-segment-elevation myocardial infarction, or the implantation of 2 different stent types. Patients were monitored for 12 months. The primary endpoint was a major adverse cardiac event, defined as a composite of death, nonfatal myocardial infarction, and target-vessel and target-lesion revascularization. Durable-polymer everolimus-eluting stents were implanted in 2,648 (81%) and biodegradable-polymer biolimus-eluting stents in 622 (19%) of the study population. There was no significant difference between the 2 groups (2.7% vs 2.7%; P=0.984) in the incidence of major adverse cardiac events. The cumulative adjusted probability of major adverse cardiac events in the biodegradable-polymer biolimus-eluting stent group did not differ from that of such events in the durable-polymer everolimus-eluting stent group (hazard ratio=0.768; 95% confidence interval, 0.421-1.44; P=0.388). We conclude that in our patients the biodegradable-polymer biolimus-eluting stent was as effective and safe, during the 12-month follow-up period, as was the durable-polymer everolimus-eluting stent.

  3. Computational modeling of biodegradable starch based polymer composites

    Science.gov (United States)

    Joshi, Sachin Sudhakar

    2007-12-01

    Purpose. The goal of this study is to improve the favorable molecular interactions between starch and PPC by addition of grafting monomers MA and ROM as compatibilizers, which would advance the mechanical properties of starch/PPC composites. Methodology. DFT and semi-empirical methods based calculations were performed on three systems: (a) starch/PPC, (b) starch/PPC-MA, and (c) starch-ROM/PPC. Theoretical computations involved the determination of optimal geometries, binding-energies and vibrational frequencies of the blended polymers. Findings. Calculations performed on five starch/PPC composites revealed hydrogen bond formation as the driving force behind stable composite formation, also confirmed by the negative relative energies of the composites indicating the existence of binding forces between the constituent co-polymers. The interaction between starch and PPC is also confirmed by the computed decrease in stretching CO and OH group frequencies participating in hydrogen bond formation, which agree qualitatively with the experimental values. A three-step mechanism of grafting MA on PPC was proposed to improve the compatibility of PPC with starch. Nine types of 'blends' produced by covalent bond formation between starch and MA-grafted PPC were found to be energetically stable, with blends involving MA grafted at the 'B' and 'C' positions of PPC indicating a binding-energy increase of 6.8 and 6.2 kcal/mol, respectively, as compared to the non-grafted starch/PPC composites. A similar increase in binding-energies was also observed for three types of 'composites' formed by hydrogen bond formation between starch and MA-grafted PPC. Next, grafting of ROM on starch and subsequent blend formation with PPC was studied. All four types of blends formed by the reaction of ROM-grafted starch with PPC were found to be more energetically stable as compared to the starch/PPC composite and starch/PPC-MA composites and blends. A blend of PPC and ROM grafted at the '

  4. Nanocomposite bone scaffolds based on biodegradable polymers and hydroxyapatite.

    Science.gov (United States)

    Becker, Johannes; Lu, Lichun; Runge, M Brett; Zeng, Heng; Yaszemski, Michael J; Dadsetan, Mahrokh

    2015-08-01

    In tissue engineering, development of an osteoconductive construct that integrates with host tissue remains a challenge. In this work, the effect of bone-like minerals on maturation of pre-osteoblast cells was investigated using polymer-mineral scaffolds composed of poly(propylene fumarate)-co-poly(caprolactone) (PPF-co-PCL) and nano-sized hydroxyapatite (HA). The HA of varying concentrations was added to an injectable formulation of PPF-co-PCL and the change in thermal and mechanical properties of the scaffolds was evaluated. No change in onset of degradation temperature was observed due to the addition of HA, however compressive and tensile moduli of copolymer changed significantly when HA amounts were increased in composite formulation. The change in mechanical properties of copolymer was found to correlate well to HA concentration in the constructs. Electron microscopy revealed mineral nucleation and a change in surface morphology and the presence of calcium and phosphate on surfaces was confirmed using energy dispersive X-ray analysis. To characterize the effect of mineral on attachment and maturation of pre-osteoblasts, W20-17 cells were seeded on HA/copolymer composites. We demonstrated that cells attached more to the surface of HA containing copolymers and their proliferation rate was significantly increased. Thus, these findings suggest that HA/PPF-co-PCL composite scaffolds are capable of inducing maturation of pre-osteoblasts and have the potential for use as scaffold in bone tissue engineering. © 2014 Wiley Periodicals, Inc.

  5. Composite implants coated with biodegradable polymers prevent stimulating tumor progression

    Energy Technology Data Exchange (ETDEWEB)

    Litviakov, N. V., E-mail: nvlitv72@yandex.ru; Tsyganov, M. M., E-mail: TsyganovMM@yandex.ru; Cherdyntseva, N. V., E-mail: nvch@oncology.tomsk.ru [Tomsk Cancer Research Institute, Tomsk, 634050 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation); Tverdokhlebov, S. I., E-mail: tverd@tpu.ru; Bolbasov, E. N., E-mail: ebolbasov@gmail.com [National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Perelmuter, V. M., E-mail: pvm@ngs.ru; Kulbakin, D. E., E-mail: kulbakin2012@gmail.com [Tomsk Cancer Research Institute, Tomsk, 634050 (Russian Federation); Zheravin, A. A., E-mail: zheravin2010@yandex.ru [Tomsk Cancer Research Institute, Tomsk, 634050 (Russian Federation); Academician E.N. Meshalkin Novosibirsk State Research Institute of Circulation Pathology, Novosibirsk (Russian Federation); Svetlichnyi, V. A., E-mail: v-svetlichnyi@bk.ru [National Research Tomsk State University, Tomsk, 634050 (Russian Federation)

    2016-08-02

    In this experiment we studied oncologic safety of model implants created using the solution blow spinning method with the use of the PURASORB PL-38 polylactic acid polymer and organic mineral filler which was obtained via laser ablation of a solid target made of dibasic calcium phosphate dihydrate. For this purpose the implant was introduced into the area of Wistar rats’ iliums, and on day 17 after the surgery the Walker sarcoma was transplanted into the area of the implant. We evaluated the implant’s influence on the primary tumor growth, hematogenous and lymphogenous metastasis of the Walker sarcoma. In comparison with sham operated animals the implant group demonstrated significant inhibition of hematogenous metastasis on day 34 after the surgery. The metastasis inhibition index (MII) equaled 94% and the metastases growth inhibition index (MGII) equaled 83%. The metastasis frequency of the Walker sarcoma in para aortic lymph nodes in the implant group was not statistically different from the control frequency; there was also no influence of the implant on the primary tumor growth noted. In case of the Walker sarcoma transplantation into the calf and the palmar pad of the ipsilateral limb to the one with the implant in the ilium, we could not note any attraction of tumor cells to the implant area, i.e. stimulation of the Walker sarcoma relapse by the implant. Thus, the research concluded that the studied implant meets the requirements of oncologic safety.

  6. Biodegradable cyclen-based linear and cross-linked polymers as non-viral gene vectors.

    Science.gov (United States)

    Li, Shuo; Wang, Yu; Wang, Shan; Zhang, Ji; Wu, Shi-Fei; Wang, Bo-Lin; Zhu, Wen; Yu, Xiao-Qi

    2012-02-15

    Several 1,4,7,10-tetraazacyclododecane (cyclen)-based linear (3a-c) and cross-linked (8a-d) polymers containing biodegradable ester or disulfide bonds were described. These polymeric compounds were prepared by ring-opening polymerization from various diol glycidyl ethers. The molecular weights of the title polymers were measured by GPC. Agarose gel retardation assays showed that these compounds have good DNA-binding ability and can completely retard plasmid DNA (pDNA) at weight ratio of 20 for linear polymers and 1.2 for cross-linked polymers. The degradation of these polymers was confirmed by GPC. The formed polyplexes have appropriate sizes around 400 nm and zeta-potential values about 15-40 mV. The cytotoxicities of 8 assayed by MTT are much lower than that of 25 KDa PEI. In vitro transfection toward A549 and 293 cells showed that the transfection efficiency (TE) of 8c-DNA polyplex is close to that of 25 kDa PEI at 8c/DNA weight ratio of 4. Structure-activity relationships (SAR) of these linear and cross-linked polymers were discussed in their DNA-binding, cytotoxicity, and transfection studies. In addition, in the presence of serum, the TE of 8/DNA polyplexes could be improved by introducing chloroquine or Ca(2+) to pretreated cells. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Investigation of Bauschinger effect in thermo-plastic polymers for biodegradable stents

    Directory of Open Access Journals (Sweden)

    Schümann Kerstin

    2017-09-01

    Full Text Available The Bauschinger effect is a phenomenon metals show as a result of plastic deformation. After a primary plastic deformation the yield strength in the opposite loading direction decreases. The aim of this study is to investigate if there is a phenomenon similar to Bauschinger effect in thermoplastic polymers for stent application that would influence the mechanical properties of these biodegradable implants. Combined uniaxial tensile with subsequent compression tests as well as conventional compression tests without prior tensile loading were performed using biodegradable polymers for stent application (PLLA and a PLLA based blend. Comparing the results of compression tests with prior tensile loading to the compression-only tests a decrease in compressive strength can be observed for both of the tested materials. The conclusion of the performed experiments is that there is a phenomenon similar to Bauschinger effect not only in metallic materials but also in the examined thermoplastic polymers. The observed reduction of compressive strength as a consequence of prior tensile loading can influence the mechanical behaviour, e.g. the radial strength, of polymeric stents after sustaining a complex load history due to crimping and expansion.

  8. Driving degradation within biodegradable polymers with embedded nanoparticles

    Science.gov (United States)

    Gorga, Russell; Firestone, Gabriel; Fontecha, Daniela; Bochinski, Jason; Clarke, Laura

    The ability to controllably trigger breaking of chemical bonds enables a substance that has robust material properties during use but can be re-worked or deteriorated upon command. Photothermal heating creates intense local heat at isolated nanoparticle locations within a sample and can result in very different material responses than those achievable with conventional (uniform) heating. In this process, irradiation with visible light resonant with the nanoparticle's surface plasmon resonance results in dramatic local heating of the particles and the surrounding material. This work studies intentional thermal degradation of poly ethyl cyanoacrylate-starch composites doped with metal nanoparticles, and explores differences in degradation speed, efficiency, and resultant mechanical properties when heated via the photothermal effect. This work was supported by the National Science Foundation, Grant #: CMMI-1462966.

  9. Fabrication of a Delaying Biodegradable Magnesium Alloy-Based Esophageal Stent via Coating Elastic Polymer

    Directory of Open Access Journals (Sweden)

    Tianwen Yuan

    2016-05-01

    Full Text Available Esophageal stent implantation can relieve esophageal stenosis and obstructions in benign esophageal strictures, and magnesium alloy stents are a good candidate because of biodegradation and biological safety. However, biodegradable esophageal stents show a poor corrosion resistance and a quick loss of mechanical support in vivo. In this study, we chose the elastic and biodegradable mixed polymer of Poly(ε-caprolactone (PCL and poly(trimethylene carbonate (PTMC as the coated membrane on magnesium alloy stents for fabricating a fully biodegradable esophageal stent, which showed an ability to delay the degradation time and maintain mechanical performance in the long term. After 48 repeated compressions, the mechanical testing demonstrated that the PCL-PTMC-coated magnesium stents possess good flexibility and elasticity, and could provide enough support against lesion compression when used in vivo. According to the in vitro degradation evaluation, the PCL-PTMC membrane coated on magnesium was a good material combination for biodegradable stents. During the in vivo evaluation, the proliferation of the smooth muscle cells showed no signs of cell toxicity. Histological examination revealed the inflammation scores at four weeks in the magnesium-(PCL-PTMC stent group were similar to those in the control group (p > 0.05. The α-smooth muscle actin layer in the media was thinner in the magnesium-(PCL-PTMC stent group than in the control group (p < 0.05. Both the epithelial and smooth muscle cell layers were significantly thinner in the magnesium-(PCL-PTMC stent group than in the control group. The stent insertion was feasible and provided reliable support for at least four weeks, without causing severe injury or collagen deposition. Thus, this stent provides a new stent for the treatment of benign esophageal stricture and a novel research path in the development of temporary stents in other cases of benign stricture.

  10. Biodegradable polymer DES versus durable polymer everolimus-eluting stents for patients undergoing PCI: a meta-analysis.

    Science.gov (United States)

    Sun, Li-Xia; Zhang, Jing

    2014-06-01

    Everolimus-eluting stents are associated with low risk of stent thrombosis and stent restenosis, and the new generation of stents with biodegradable polymer were designed to reduce that risk. However, the benefits have been variable. Four RCTs with a total of 8282 patients were included. Overall, BP-DES was not inferior to EES with equivalent risk of TVR (relative risk [RR], 1.07; 95% confidence interval [CI], 0.91-1.27; P=0.414; I(2)=0.0%) and ARC definite and/or probable ST (RR, 1.06; 95% CI, 0.66-1.70; P=0.810; I(2)=4.8%). Furthermore, there was no difference in all-cause mortality (RR, 1.06; 95% CI, 0.84-1.33; P=0.651; I(2)=0.0%), myocardial infarction (RR, 1.12; 95% CI, 0.88-1.44; P=0.360; I(2)=0.0%), and MACE (RR, 1.00; 95% CI, 0.87-1.15; P=0.975; I(2)=0.0%) between the two groups. The new generation of biodegradable polymer stents were not inferior to EES for equivalent risk of MACE and ST. Copyright © 2014 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

  11. Polymer-Particle Pressure-Sensitive Paint with High Photostability

    Directory of Open Access Journals (Sweden)

    Yu Matsuda

    2016-04-01

    Full Text Available We propose a novel fast-responding and paintable pressure-sensitive paint (PSP based on polymer particles, i.e. polymer-particle (pp-PSP. As a fast-responding PSP, polymer-ceramic (PC-PSP is widely studied. Since PC-PSP generally consists of titanium (IV oxide (TiO2 particles, a large reduction in the luminescent intensity will occur due to the photocatalytic action of TiO2. We propose the usage of polymer particles instead of TiO2 particles to prevent the reduction in the luminescent intensity. Here, we fabricate pp-PSP based on the polystyrene particle with a diameter of 1 μm, and investigate the pressure- and temperature-sensitives, the response time, and the photostability. The performances of pp-PSP are compared with those of PC-PSP, indicating the high photostability with the other characteristics comparable to PC-PSP.

  12. Panorama setorial e perspectivas na área de polímeros biodegradáveis Biodegradable polymers: sectorial overview and prospects

    Directory of Open Access Journals (Sweden)

    Daniele M. B. Falcone

    2007-03-01

    Full Text Available Neste trabalho, envolvendo polímeros biodegradáveis, buscou-se obter indicadores por meio da análise de patentes para avaliar as perspectivas e oportunidades de atuação da área de polímeros. Utilizou-se para tal a base de dados Espacenet e o software Vantage Point. São matéria desse estudo os polímeros: poli(hidroxibutirato - PHB, poli(hidroxibutirato-co-hidroxivalerato - PHBV, poli(ácido lático - PLA, poli(épsilon-caprolactona - PCL e os polihidroxialcanoatos (PHAs, tratados mais detalhadamente por serem a classe geral dos poliésteres microbiais. Verificou-se que a área de polímeros biodegradáveis, apesar de recente e em desenvolvimento, apresenta grande potencial mediante o panorama atual de consumo dos materiais poliméricos. Observou-se, de uma forma geral, uma grande diversidade de temas e oportunidades de estudo em compostos, blendas, biodegradação e aplicações.This work on biodegradable polymers involved an analysis of patents to identify indicators for evaluating the prospects and opportunities of action in the field of polymers. We used the Spacenet database and Vantage Point software. The study encompassed the following polymers: polyhydroxybutyrate - PHB, polyhydroxybutyrate-co-hydroxyvalerate - PHBV, polylactic acid - PLA, poly (epsilon-caprolactone - PCL and the polyhydroxyalkanoates (PHAs, dealt in greater detail because they represent the general class of microbial polyesters. We found that, although the field of biodegradable polymers is new and still under development, it holds great potential in view of present widespread use of polymeric materials. Overall we found a great diversity of themes and opportunities for studies on compounds, blends, biodegradation and applications.

  13. Alternating-current electrophoretic adhesion of biodegradable hydrogel utilizing intermediate polymers.

    Science.gov (United States)

    Asoh, Taka-Aki; Kawai, Wataru; Kikuchi, Akihiko

    2014-11-01

    The adhesion of anionic charged biodegradable hydrogels each other utilizing oppositely charged water-soluble polymers as a binder has been achieved by applying alternating-current (AC) electric fields. The two gelatin based dextran sulfate gels (DS gels) were molecularly sutured together by AC electrophoretic adhesion when cationic charged quaternary ammonium chitosan (TMC) was applied between and held in contact with the two DS gels. The adhesive strength of the gels increased with increasing periodicity when a square wave was applied. Hydrogel constructs composed of DS microgels were prepared simply by AC electrophoretic adhesion utilizing intermediate TMC. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Biodegradable Polymer Releasing Antibiotic Developed for Drainage Catheter of Cerebrospinal Fluid: In Vitro Results

    Science.gov (United States)

    Han, Song Yup; Cho, Ki Hong; Cho, Han Jin; An, Jeong Ho; Ra, Young Sin

    2005-01-01

    The authors developed a biodegradable polymer that releases an antibiotic (nalidixic acid) slowly and continuously, for prevention of catheter-induced infection during drainage of cerebrospinal fluid. We investigated the in vitro antibiotic releasing characteristics and bacterial killing effects of the new polymer against E. coli. The novel fluoroquinolone polymer was prepared using diisopropylcarbodiimide, poly (e-caprolactone) diol, and nalidixic acid. FT-IR, mass spectrometry, and elemental analysis proved that the novel antibacterial polymer was prepared successfully without any side products. Negative MS showed that the released drug has a similar molecular weight (M.W.=232, 350) to pure drug (M.W.=232). In high pressure liquid chromatography, the released drug and drug-oligomer showed similar retention times (about 4.5-5 min) in comparison to pure drug (4.5 min). The released nalidixic acid and nalidixic acid derivatives have antibacterial characteristics against E. coli, Staphylococcus aureus, and Salmonella typhi, of more than 3 months duration. This study suggests the possibility of applying this new polymer to manufacture drainage catheters that resist catheter-induced infection, by delivering antibiotics for a longer period of more than 1 month. PMID:15832004

  15. Mechanical, Thermomechanical and Reprocessing Behavior of Green Composites from Biodegradable Polymer and Wood Flour.

    Science.gov (United States)

    Morreale, Marco; Liga, Antonio; Mistretta, Maria Chiara; Ascione, Laura; Mantia, Francesco Paolo La

    2015-11-11

    The rising concerns in terms of environmental protection and the search for more versatile polymer-based materials have led to an increasing interest in the use of polymer composites filled with natural organic fillers (biodegradable and/or coming from renewable resources) as a replacement for traditional mineral inorganic fillers. At the same time, the recycling of polymers is still of fundamental importance in order to optimize the utilization of available resources, reducing the environmental impact related to the life cycle of polymer-based items. Green composites from biopolymer matrix and wood flour were prepared and the investigation focused on several issues, such as the effect of reprocessing on the matrix properties, wood flour loading effects on virgin and reprocessed biopolymer, and wood flour effects on material reprocessability. Tensile, Dynamic-mechanical thermal (DMTA), differential scanning calorimetry (DSC) and creep tests were performed, pointing out that wood flour leads to an improvement of rigidity and creep resistance in comparison to the pristine polymer, without compromising other properties such as the tensile strength. The biopolymer also showed a good resistance to multiple reprocessing; the latter even allowed for improving some properties of the obtained green composites.

  16. Mechanical, Thermomechanical and Reprocessing Behavior of Green Composites from Biodegradable Polymer and Wood Flour

    Directory of Open Access Journals (Sweden)

    Marco Morreale

    2015-11-01

    Full Text Available The rising concerns in terms of environmental protection and the search for more versatile polymer-based materials have led to an increasing interest in the use of polymer composites filled with natural organic fillers (biodegradable and/or coming from renewable resources as a replacement for traditional mineral inorganic fillers. At the same time, the recycling of polymers is still of fundamental importance in order to optimize the utilization of available resources, reducing the environmental impact related to the life cycle of polymer-based items. Green composites from biopolymer matrix and wood flour were prepared and the investigation focused on several issues, such as the effect of reprocessing on the matrix properties, wood flour loading effects on virgin and reprocessed biopolymer, and wood flour effects on material reprocessability. Tensile, Dynamic-mechanical thermal (DMTA, differential scanning calorimetry (DSC and creep tests were performed, pointing out that wood flour leads to an improvement of rigidity and creep resistance in comparison to the pristine polymer, without compromising other properties such as the tensile strength. The biopolymer also showed a good resistance to multiple reprocessing; the latter even allowed for improving some properties of the obtained green composites.

  17. Synthesis, Properties and Applications of Biodegradable Polymers Derived from Diols and Dicarboxylic Acids: From Polyesters to Poly(ester amides

    Directory of Open Access Journals (Sweden)

    Angélica Díaz

    2014-04-01

    Full Text Available Poly(alkylene dicarboxylates constitute a family of biodegradable polymers with increasing interest for both commodity and speciality applications. Most of these polymers can be prepared from biobased diols and dicarboxylic acids such as 1,4-butanediol, succinic acid and carbohydrates. This review provides a current status report concerning synthesis, biodegradation and applications of a series of polymers that cover a wide range of properties, namely, materials from elastomeric to rigid characteristics that are suitable for applications such as hydrogels, soft tissue engineering, drug delivery systems and liquid crystals. Finally, the incorporation of aromatic units and α-amino acids is considered since stiffness of molecular chains and intermolecular interactions can be drastically changed. In fact, poly(ester amides derived from naturally occurring amino acids offer great possibilities as biodegradable materials for biomedical applications which are also extensively discussed.

  18. Biocompatible or biodegradable hyperbranched polymers: from self-assembly to cytomimetic applications.

    Science.gov (United States)

    Jin, Haibao; Huang, Wei; Zhu, Xinyuan; Zhou, Yongfeng; Yan, Deyue

    2012-09-21

    Self-assembly of amphiphilic hyperbranched polymers (HBPs) is a newly emerging research area and has attracted increasing attention due to the great advantages in biomedical applications. This tutorial review focuses on the self-assembly of biocompatible or biodegradable amphiphilic HBPs and their cytomimetic applications, and specialities or advantages therein owing to the hyperbranched structure have also been summarized. As shown here, various supramolecular structures including micelles, vesicles, tubes, fibers and films have been prepared through the primary self-assembly processes. The primary self-assemblies can be further assembled into more complex structures through hierachical self-assembly processes. Besides, the hyperbranched polymer vesicles have demonstrated great potential to be used as model membranes to mimic cellular behaviors, such as fusion, fission and cell aggregation. Other biomedical applications of HBPs as well as their self-assemblies are also briefly summarized.

  19. Carbon-rich wastes as feedstocks for biodegradable polymer (polyhydroxyalkanoate) production using bacteria.

    Science.gov (United States)

    Nikodinovic-Runic, Jasmina; Guzik, Maciej; Kenny, Shane T; Babu, Ramesh; Werker, Alan; O Connor, Kevin E

    2013-01-01

    Research into the production of biodegradable polymers has been driven by vision for the most part from changes in policy, in Europe and America. These policies have their origins in the Brundtland Report of 1987, which provides a platform for a more sustainable society. Biodegradable polymers are part of the emerging portfolio of renewable raw materials seeking to deliver environmental, social, and economic benefits. Polyhydroxyalkanoates (PHAs) are naturally-occurring biodegradable-polyesters accumulated by bacteria usually in response to inorganic nutrient limitation in the presence of excess carbon. Most of the early research into PHA accumulation and technology development for industrial-scale production was undertaken using virgin starting materials. For example, polyhydroxybutyrate and copolymers such as polyhydroxybutyrate-co-valerate are produced today at industrial scale from corn-derived glucose. However, in recent years, research has been undertaken to convert domestic and industrial wastes to PHA. These wastes in today's context are residuals seen by a growing body of stakeholders as platform resources for a biobased society. In the present review, we consider residuals from food, plastic, forest and lignocellulosic, and biodiesel manufacturing (glycerol). Thus, this review seeks to gain perspective of opportunities from literature reporting the production of PHA from carbon-rich residuals as feedstocks. A discussion on approaches and context for PHA production with reference to pure- and mixed-culture technologies is provided. Literature reports advocate results of the promise of waste conversion to PHA. However, the vast majority of studies on waste to PHA is at laboratory scale. The questions of surmounting the technical and political hurdles to industrialization are generally left unanswered. There are a limited number of studies that have progressed into fermentors and a dearth of pilot-scale demonstration. A number of fermentation studies show

  20. Numerical study on injection parameters optimization of thin wall and biodegradable polymers parts

    Science.gov (United States)

    Santos, C.; Mendes, A.; Carreira, P.; Mateus, A.; Malça, C.

    2017-07-01

    Nowadays, the molds industry searches new markets, with diversified and added value products. The concept associated to the production of thin walled and biodegradable parts mostly manufactured by injection process has assumed a relevant importance due to environmental and economic factors. The growth of a global consciousness about the harmful effects of the conventional polymers in our life quality associated with the legislation imposed, become key factors for the choice of a particular product by the consumer. The target of this work is to provide an integrated solution for the injection of parts with thin walls and manufactured using biodegradable materials. This integrated solution includes the design and manufacture processes of the mold as well as to find the optimum values for the injection parameters in order to become the process effective and competitive. For this, the Moldflow software was used. It was demonstrated that this computational tool provides an effective responsiveness and it can constitute an important tool in supporting the injection molding of thin-walled and biodegradable parts.

  1. Effect of sterilization dose on electron beam irradiated biodegradable polymers and coconut fiber based composites

    International Nuclear Information System (INIS)

    Kodama, Yasko; Machado, Luci D.B.; Oishi, Akihiro; Nakayama, Kazuo; Nagasawa, Naotsugu; Tamada, Masao

    2009-01-01

    In Brazil, annual production of coconut fruit is 1.5 billion in a cultivated area of 2.7 million ha. Coconut fiber applications as reinforcement for polymer composites, besides reducing the coconut waste, would reduce cost of the composite. On the other hand, biodegradable polymers have been receiving much attention due to the plastic waste problem. Poly(e-caprolactone), PCL, and poly(lactic acid), PLA, besides being biodegradable aliphatic polyesters, are biocompatible polymers. Considering the biomedical application of PLA and PCL, their products must be sterilized for use, and ionizing radiation has been widely used for medical devices sterilization. It is important to study the effect of ionizing radiation on the blends and composites due to the fact that they are based on biocompatible polymers. Is this research, hot pressed samples based on PLA:PCL (80:20, ratio of weight:weight) blend and the composites containing chemically treated or untreated coconut fiber (5, 10%) were irradiated by electron beams and gamma radiation from Co-60 source at doses in the range up to 200 kGy. Thermal mechanical analysis (TMA) and gel fraction measurements were performed in irradiated samples. From TMA curves it can be observed that thermal stability of samples with untreated coconut fiber slightly decreased with increasing fiber content. On the other hand, deformation increased with increasing fiber content. Acetylated coconut fibers slightly decreased thermal stability of samples. It seems that no interaction occurs between the natural fibers and the polymeric matrix due to irradiation. PLLA undergoes to main chain scission under ionizing irradiation according to thermal stability results and also because no gel fraction was observed. In contrast, PCL cross-linking is induced by ionizing radiation that increases thermal stability and decreases deformation. (author)

  2. Effect of sterilization dose on electron beam irradiated biodegradable polymers and coconut fiber based composites

    Energy Technology Data Exchange (ETDEWEB)

    Kodama, Yasko; Machado, Luci D.B., E-mail: ykodama@ipen.b, E-mail: lmachado@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Oishi, Akihiro; Nakayama, Kazuo, E-mail: a.oishi@aist.go.j, E-mail: kazuo-nakayama@jcom.home.ne.j [National Institute of Advanced Industrial Science and Technology (AIST), Ibaraki-ken (Japan). Research Institute for Sustainable Chemical Innovation; Nagasawa, Naotsugu; Tamada, Masao, E-mail: nagasawa.naotsugu@jaea.go.j [Japan Atomic Energy Agency (JAEA), Gunma-ken (Japan). Quantum Beam Science Directorate

    2009-07-01

    In Brazil, annual production of coconut fruit is 1.5 billion in a cultivated area of 2.7 million ha. Coconut fiber applications as reinforcement for polymer composites, besides reducing the coconut waste, would reduce cost of the composite. On the other hand, biodegradable polymers have been receiving much attention due to the plastic waste problem. Poly(e-caprolactone), PCL, and poly(lactic acid), PLA, besides being biodegradable aliphatic polyesters, are biocompatible polymers. Considering the biomedical application of PLA and PCL, their products must be sterilized for use, and ionizing radiation has been widely used for medical devices sterilization. It is important to study the effect of ionizing radiation on the blends and composites due to the fact that they are based on biocompatible polymers. Is this research, hot pressed samples based on PLA:PCL (80:20, ratio of weight:weight) blend and the composites containing chemically treated or untreated coconut fiber (5, 10%) were irradiated by electron beams and gamma radiation from Co-60 source at doses in the range up to 200 kGy. Thermal mechanical analysis (TMA) and gel fraction measurements were performed in irradiated samples. From TMA curves it can be observed that thermal stability of samples with untreated coconut fiber slightly decreased with increasing fiber content. On the other hand, deformation increased with increasing fiber content. Acetylated coconut fibers slightly decreased thermal stability of samples. It seems that no interaction occurs between the natural fibers and the polymeric matrix due to irradiation. PLLA undergoes to main chain scission under ionizing irradiation according to thermal stability results and also because no gel fraction was observed. In contrast, PCL cross-linking is induced by ionizing radiation that increases thermal stability and decreases deformation. (author)

  3. Surface Modification of Biodegradable Polymers towards Better Biocompatibility and Lower Thrombogenicity.

    Science.gov (United States)

    Rudolph, Andreas; Teske, Michael; Illner, Sabine; Kiefel, Volker; Sternberg, Katrin; Grabow, Niels; Wree, Andreas; Hovakimyan, Marina

    2015-01-01

    Drug-eluting stents (DES) based on permanent polymeric coating matrices have been introduced to overcome the in stent restenosis associated with bare metal stents (BMS). A further step was the development of DES with biodegradable polymeric coatings to address the risk of thrombosis associated with first-generation DES. In this study we evaluate the biocompatibility of biodegradable polymer materials for their potential use as coating matrices for DES or as materials for fully bioabsorbable vascular stents. Five different polymers, poly(L-lactide) PLLA, poly(D,L-lactide) PDLLA, poly(L-lactide-co-glycolide) P(LLA-co-GA), poly(D,L-lactide-co-glycolide) P(DLLA-co-GA) and poly(L-lactide-co-ε-caprolactone), P(LLA-co-CL) were examined in vitro without and with surface modification. The surface modification of polymers was performed by means of wet-chemical (NaOH and ethylenediamine (EDA)) and plasma-chemical (O2 and NH3) processes. The biocompatibility studies were performed on three different cell types: immortalized mouse fibroblasts (cell line L929), human coronary artery endothelial cells (HCAEC) and human umbilical vein endothelial cells (HUVEC). The biocompatibility was examined quantitatively using in vitro cytotoxicity assay. Cells were investigated immunocytochemically for expression of specific markers, and morphology was visualized using confocal laser scanning (CLSM) and scanning electron (SEM) microscopy. Additionally, polymer surfaces were examined for their thrombogenicity using an established hemocompatibility test. Both endothelial cell types exhibited poor viability and adhesion on all five unmodified polymer surfaces. The biocompatibility of the polymers could be influenced positively by surface modifications. In particular, a reproducible effect was observed for NH3-plasma treatment, which enhanced the cell viability, adhesion and morphology on all five polymeric surfaces. Surface modification of polymers can provide a useful approach to enhance

  4. Surface Modification of Biodegradable Polymers towards Better Biocompatibility and Lower Thrombogenicity

    Science.gov (United States)

    Rudolph, Andreas; Teske, Michael; Illner, Sabine; Kiefel, Volker; Sternberg, Katrin; Grabow, Niels; Wree, Andreas; Hovakimyan, Marina

    2015-01-01

    Purpose Drug-eluting stents (DES) based on permanent polymeric coating matrices have been introduced to overcome the in stent restenosis associated with bare metal stents (BMS). A further step was the development of DES with biodegradable polymeric coatings to address the risk of thrombosis associated with first-generation DES. In this study we evaluate the biocompatibility of biodegradable polymer materials for their potential use as coating matrices for DES or as materials for fully bioabsorbable vascular stents. Materials and Methods Five different polymers, poly(L-lactide) PLLA, poly(D,L-lactide) PDLLA, poly(L-lactide-co-glycolide) P(LLA-co-GA), poly(D,L-lactide-co-glycolide) P(DLLA-co-GA) and poly(L-lactide-co-ε-caprolactone), P(LLA-co-CL) were examined in vitro without and with surface modification. The surface modification of polymers was performed by means of wet-chemical (NaOH and ethylenediamine (EDA)) and plasma-chemical (O2 and NH3) processes. The biocompatibility studies were performed on three different cell types: immortalized mouse fibroblasts (cell line L929), human coronary artery endothelial cells (HCAEC) and human umbilical vein endothelial cells (HUVEC). The biocompatibility was examined quantitatively using in vitro cytotoxicity assay. Cells were investigated immunocytochemically for expression of specific markers, and morphology was visualized using confocal laser scanning (CLSM) and scanning electron (SEM) microscopy. Additionally, polymer surfaces were examined for their thrombogenicity using an established hemocompatibility test. Results Both endothelial cell types exhibited poor viability and adhesion on all five unmodified polymer surfaces. The biocompatibility of the polymers could be influenced positively by surface modifications. In particular, a reproducible effect was observed for NH3-plasma treatment, which enhanced the cell viability, adhesion and morphology on all five polymeric surfaces. Conclusion Surface modification of

  5. Antibacterial and anti-encrustation biodegradable polymer coating for urinary catheter.

    Science.gov (United States)

    Dayyoub, Eyas; Frant, Marion; Pinnapireddy, Shashank Reddy; Liefeith, Klaus; Bakowsky, Udo

    2017-10-05

    Bacterial biofilm and crystalline deposits are the common causes of failure of long-term indwelling urinary catheter. Bacteria colonise the catheter surface causing serious infections in the urinary tract and encrustations that can block the catheter and induce trauma in patients. In this study, the strategy used to resist bacterial adhesion and encrustation represents a combination of the antibacterial effects of norfloxacin and silver nanoparticles and the PLGA-based neutralisation of alkali products of urea hydrolysis gained through the degradation of the polymer in an aqueous milieu. Silver nanoparticles were coated with tetraether lipids (TEL) to avoid aggregation when dispersed in acetone and during the film formation. The polymer films loaded with the two antibacterial agents were applied on Polyurethane (PUR) and Silicon sheets. We demonstrated the antibacterial and anti-adhesion effectiveness of the coatings whereby commercially available biocompatible polymers PUR and Silicon were used as controls. Using artificial urine and an in vitro encrustation model, it was shown that the coatings resist the encrustation for at least 2 weeks. This combination of a biodegradable polymer and wide-range antibacterial agents represents a potentially attractive biocompatible coating for urinary catheters. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Electrical properties of biodegradable poly(ε-caprolactone): lithium thiocyanate complexed polymer electrolyte films

    Energy Technology Data Exchange (ETDEWEB)

    Ravi, M. [Shenzhen Key Laboratory of Advanced Materials, Department of Materials Science and Engineering, Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Song, Shenhua, E-mail: shsonguk@aliyun.com [Shenzhen Key Laboratory of Advanced Materials, Department of Materials Science and Engineering, Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Gu, Kunming; Tang, Jiaoning [College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060 (China); Zhang, Zhongyi [Advanced Polymer and Composites (APC) Research Group, School of Engineering, University of Portsmouth, Portsmouth PO1 3DJ, Hampshire (United Kingdom)

    2015-05-15

    Graphical abstract: - Highlights: • The minimum T{sub m} and χ{sub c} values are observed in 15 wt% LiSCN complexed film. • The conductivity of PCL:LiSCN complexed films follows Johnscher's power law. • Conductivity and dielectric constant follows the same trend. • The charge carriers responsible for both conduction and relaxation are the same. - Abstract: Lithium ion conducting polymer electrolyte films based on biodegradable poly(ε-caprolactone) (PCL) complexed with lithium thiocyanate (LiSCN) salt were prepared by solution cast technique. Thermal and electrical properties of the polymer electrolyte films were studied using differential scanning calorimetry (DSC) and ac impedance spectroscopy. In order to investigate the ion conduction mechanism and relaxation behavior of complex polymer electrolyte films, the conductivity, dielectric constant, loss tangent and electric modulus were analyzed as a function of frequency and temperature. The variation of conductivity with frequency obeyed the Johnscher's power law. The dielectric constant exhibited a higher value at a lower frequency and increased with rising temperature due to the polar nature of host polymer. The activation energies for both dc conductivity and relaxation had the same value (∼0.87 eV), implying that the charge carriers responsible for both conduction and relaxation were the same.

  7. Electrical properties of biodegradable poly(ε-caprolactone): lithium thiocyanate complexed polymer electrolyte films

    International Nuclear Information System (INIS)

    Ravi, M.; Song, Shenhua; Gu, Kunming; Tang, Jiaoning; Zhang, Zhongyi

    2015-01-01

    Graphical abstract: - Highlights: • The minimum T m and χ c values are observed in 15 wt% LiSCN complexed film. • The conductivity of PCL:LiSCN complexed films follows Johnscher's power law. • Conductivity and dielectric constant follows the same trend. • The charge carriers responsible for both conduction and relaxation are the same. - Abstract: Lithium ion conducting polymer electrolyte films based on biodegradable poly(ε-caprolactone) (PCL) complexed with lithium thiocyanate (LiSCN) salt were prepared by solution cast technique. Thermal and electrical properties of the polymer electrolyte films were studied using differential scanning calorimetry (DSC) and ac impedance spectroscopy. In order to investigate the ion conduction mechanism and relaxation behavior of complex polymer electrolyte films, the conductivity, dielectric constant, loss tangent and electric modulus were analyzed as a function of frequency and temperature. The variation of conductivity with frequency obeyed the Johnscher's power law. The dielectric constant exhibited a higher value at a lower frequency and increased with rising temperature due to the polar nature of host polymer. The activation energies for both dc conductivity and relaxation had the same value (∼0.87 eV), implying that the charge carriers responsible for both conduction and relaxation were the same

  8. Unique morphology of dispersed clay particles in a polymer nanocomposite

    CSIR Research Space (South Africa)

    Malwela, T

    2011-02-01

    Full Text Available This communication reports a unique morphology of dispersed clay particles in a polymer nanocomposite. A nanocomposite of poly[butylene succinate)-co-adipate] (PBSA) with 3 wt% of organically modified montmorillonite was prepared by melt...

  9. Final five-year outcomes after implantation of biodegradable polymer-coated biolimus-eluting stents versus durable polymer-coated sirolimus-eluting stents

    DEFF Research Database (Denmark)

    Jakobsen, Lars; Christiansen, Evald H; Maeng, Michael

    2017-01-01

    AIMS: Our aim was to report the long-term safety and efficacy of the biodegradable polymer-coated biolimus- eluting Nobori stent compared to the durable polymer-coated sirolimus-eluting CYPHER stent. METHODS AND RESULTS: SORT OUT V randomised 2,468 patients 1:1 to the Nobori (n=1,229) versus...... also found to be similar in patients treated with the two study stents (Nobori 23/1,229 [1.9%] vs. CYPHER 18/1,239 [1.5%]; OR 1.31, 95% CI: 0.70-2.47; p=0.40), as were the other secondary endpoints. CONCLUSIONS: At five-year follow-up, the Nobori stent with a biodegradable polymer coating provided...... a similar safety and efficacy profile when compared to the durable polymer first-generation CYPHER stent....

  10. Development of polymer films by the coalescence of polymer particles in powdered and aqueous polymer-modified mortars

    International Nuclear Information System (INIS)

    Afridi, M.U.K.; Ohama, Y.; Demura, K.; Iqbal, M.Z.

    2003-01-01

    This paper evaluates and compares the coalescence of polymer particles (continuous polymer films formation) in powdered polymer-modified mortars (PPMMs) and aqueous polymer-modified mortars (APMMs). Polymer-modified mortars (PMMs) using various redispersible polymer powders (powdered cement modifiers) and polymer dispersions (aqueous cement modifiers) were prepared by varying the polymer-cement ratio (P/C) and were tested for the characterization of polymer films using a scanning electron microscope (SEM) after curing for 28 days. It is concluded from the test results that mortar constituents of unmodified mortar (UMM) are loosely joined with each other due to the absence of polymer films, thus having a structure with comparatively lower mechanical and durability characteristics. By contrast, mortar constituents in PPMMs and APMMs are compactly joined with each other due to the presence of interweaving polymer films, thereby forming a monolithic structure with improved mechanical and durability characteristics. However, the results make obvious the poor coalescence of polymer particles or development of inferior quality polymers films in PPMMs as compared to that observed in APMMs. Moreover, PPMMs show less uniform distribution of polymer films as compared to that in APMMs. Different powdered cement modifiers have different film-forming capabilities. However, such difference is hardly recognized in aqueous cement modifiers. The polymer films in PPMMs and APMMs may acquire different structures. They may appear as mesh-like, thread-like, rugged, dense or fibrous with fine or rough surfaces. Development of coherent polymer films is not well pronounced at a P/C of 5% in PPMMs, whereas sometimes coherent polymer films are observed at a P/C of 5% in APMMs. At a P/C of 10% or more, fully developed, coherent polymer films are observed in both PPMMs and APMMs

  11. Effect of degumming time on silkworm silk fibre for biodegradable polymer composites

    Science.gov (United States)

    Ho, Mei-po; Wang, Hao; Lau, Kin-tak

    2012-02-01

    Recently, many studies have been conducted on exploitation of natural materials for modern product development and bioengineering applications. Apart from plant-based materials (such as sisal, hemp, jute, bamboo and palm fibre), animal-based fibre is a kind of sustainable natural materials for making novel composites. Silkworm silk fibre extracted from cocoon has been well recognized as a promising material for bio-medical engineering applications because of its superior mechanical and bioresorbable properties. However, when producing silk fibre reinforced biodegradable/bioresorbable polymer composites, hydrophilic sericin has been found to cause poor interfacial bonding with most polymers and thus, it results in affecting the resultant properties of the composites. Besides, sericin layers on fibroin surface may also cause an adverse effect towards biocompatibility and hypersensitivity to silk for implant applications. Therefore, a proper pre-treatment should be done for sericin removal. Degumming is a surface modification process which allows a wide control of the silk fibre's properties, making the silk fibre possible to be used for the development and production of novel bio-composites with unique/specific mechanical and biodegradable properties. In this paper, a cleaner and environmentally friendly surface modification technique for tussah silk in polymer based composites is proposed. The effectiveness of different degumming parameters including degumming time and temperature on tussah silk is discussed through the analyses of their mechanical and morphological properties. Based on results obtained, it was found that the mechanical properties of tussah silk are affected by the degumming time due to the change of the fibre structure and fibroin alignment.

  12. Interaction of polymer with discotic clay particles

    International Nuclear Information System (INIS)

    Auvray, L.; Lal, J.

    1999-01-01

    Normally synthetic well defined monodisperse discotic laponite clays are known to form a gel phase at mass concentrations as low as a few percent in distilled water. Hydrosoluble polymer polyethylene oxide was added to this intriguing clay system, it was observed that it either prevents gelation or slows it down extremely depending on the polymer weight, concentration or the laponite concentration. Small Angle Neutron scattering (SANS) was used to study these systems because only by isotopic labeling can the structure of the adsorbed polymer layers be determined. The contrast variation technique is specifically used to determine separately the different partial structure factors of the clay and polymer. In this way the signal of the adsorbed chains is separated from the signal of the free chains in the dilute regime. Attempts have also been made to characterize the structure in the concentrated regime of laponite with polymer

  13. Radiation processing of indigenous natural polymers. Properties of radiation modified blends from sago-starch for biodegradable composite

    International Nuclear Information System (INIS)

    Ghazali, Z.; Dahlan, K.Z.; Wongsuban, B.; Idris, S.; Muhammad, K.

    2001-01-01

    Research and development on biodegradable polymer blends and composites have gained wider interest to offer alternative eco-friendly products. Natural polysaccharide such as sago-starch offers the most promising raw material for the production of biodegradable composites. The potential of sago, which is so abundant in Malaysia, to produce blends for subsequent applications in composite material, was evaluated and explored. Blends with various formulations of sago starch and polyvinyl alcohol (PVA), and polyvinyl pyrrolidone (PVP) polymers were prepared and subjected to radiation modification using electron beam irradiation. The effect of irradiation on the sago and its blends was evaluated and their properties were characterized. The potential of producing composite from sago blends was explored. Foams from these blends were produced using microwave oven while films were produced through casting method. The properties such as mechanical, water absorption, expansion ratio, and biodegradability were characterized and reported in this paper. (author)

  14. Novel application of a Fe-Zn double-metal cyanide catalyst in the synthesis of biodegradable, hyperbranched polymers.

    Science.gov (United States)

    Sebastian, Joby; Srinivas, Darbha

    2011-10-07

    The use of Fe-Zn double-metal cyanide as a solid catalyst for synthesizing biodegradable, hyperbranched polymers from diacids and glycerol has been reported, for the first time, wherein acidity, micro-mesoporosity and hydrophobicity of the catalyst played an important role in controlling gelation. This journal is © The Royal Society of Chemistry 2011

  15. A Review on Recent Advances in Stabilizing Peptides/Proteins upon Fabrication in Hydrogels from Biodegradable Polymers

    OpenAIRE

    Faisal Raza; Hajra Zafar; Ying Zhu; Yuan Ren; Aftab -Ullah; Asif Ullah Khan; Xinyi He; Han Han; Md Aquib; Kofi Oti Boakye-Yiadom; Liang Ge

    2018-01-01

    Hydrogels evolved as an outstanding carrier material for local and controlled drug delivery that tend to overcome the shortcomings of old conventional dosage forms for small drugs (NSAIDS) and large peptides and proteins. The aqueous swellable and crosslinked polymeric network structure of hydrogels is composed of various natural, synthetic and semisynthetic biodegradable polymers. Hydrogels have remarkable properties of functionality, reversibility, sterilizability, and biocompatibility. All...

  16. Control of enzymatic degradation of biodegradable polymers by treatment with biosurfactants, mannosylerythritol lipids, derived from Pseudozyma spp. yeast strains.

    Science.gov (United States)

    Fukuoka, Tokuma; Shinozaki, Yukiko; Tsuchiya, Wataru; Suzuki, Ken; Watanabe, Takashi; Yamazaki, Toshimasa; Kitamoto, Dai; Kitamoto, Hiroko

    2016-02-01

    Cutinase-like esterase from the yeasts Pseudozyma antarctica (PaE) shows strong degradation activity in an agricultural biodegradable plastic (BP) model of mulch films composed of poly(butylene succinate-co-adipate) (PBSA). P. antarctica is known to abundantly produce a glycolipid biosurfactant, mannosylerythritol lipid (MEL). Here, the effects of MEL on PaE-catalyzed degradation of BPs were investigated. Based on PBSA dispersion solution, the degradation of PBSA particles by PaE was inhibited in the presence of MEL. MEL behavior on BP substrates was monitored by surface plasmon resonance (SPR) using a sensor chip coated with polymer films. The positive SPR signal shift indicated that MEL readily adsorbed and spread onto the surface of a BP film. The amount of BP degradation by PaE was monitored based on the negative SPR signal shift and was decreased 1.7-fold by MEL pretreatment. Furthermore, the shape of PBSA mulch films in PaE-containing solution was maintained with MEL pretreatment, whereas untreated films were almost completely degraded and dissolved. These results suggest that MEL covering the surface of BP film inhibits adsorption of PaE and PaE-catalyzed degradation of BPs. We applied the above results to control the microbial degradation of BP mulch films. MEL pretreatment significantly inhibited BP mulch film degradation by both PaE solution and BP-degradable microorganism. Moreover, the degradation of these films was recovered after removal of the coated MEL by ethanol treatment. These results demonstrate that the biodegradation of BP films can be readily and reversibly controlled by a physical approach using MEL.

  17. Biodegradable polymer brush as nanocoupled interface for improving the durability of polymer coating on metal surface.

    Science.gov (United States)

    Bedair, Tarek M; Cho, Youngjin; Joung, Yoon Ki; Han, Dong Keun

    2014-10-01

    Metal-based drug-eluting stents (DESs) have severe drawbacks such as peeling-off and cracking of the coated polymer. To prevent the fracture of polymer-coated layer and improve the durability of DES, poly(l-lactide) (PLLA) brushes were synthesized onto cobalt-chromium (Co-Cr or CC) surface through atom transfer radical polymerization (ATRP) of 2-hydroxyethylmethacrylate (HEMA) followed by surface-initiated ring opening polymerization (SI-ROP) of l-lactide. The polymer brushes were then characterized by attenuated total reflection-Fourier transform infrared (ATR-FTIR), water contact angle, ellipsometry, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM). All of the unmodified and modified Co-Cr surfaces were coated with a matrix of poly(d,l-lactide) (PDLLA) and sirolimus (SRL). The in vitro drug release profile was measured for 70 days. The PLLA-modified Co-Cr showed a biphasic release pattern in the initial burst followed by a slow release. On the other hand, the unmodified Co-Cr showed fast drug release and detachment of the coated polymer layer due to the instability of the polymer layer on Co-Cr surface. In comparison, the PLLA-modified Co-Cr preserved a uniform coating without detachment even after 6 weeks of degradation test. The platelet morphology and low density of platelet adhered on the modified layer and the SRL-in-PDLLA coated Co-Cr surfaces demonstrated that these samples would be blood compatible. Therefore, the introduction of PLLA brush onto Co-Cr surface is proved to dramatically improve the durability of the coating layer, and it is a promising strategy to prevent the coating defects found in DESs. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. A life cycle framework to support materials selection for Ecodesign: A case study on biodegradable polymers

    International Nuclear Information System (INIS)

    Ribeiro, I.; Peças, P.; Henriques, E.

    2013-01-01

    Highlights: • Life cycle framework to support material selection in Ecodesign. • Early design stage estimates and sensitivity analyses based on process-based models. • Sensitivity analysis to product geometry, industrial context and EoL scenarios. • Cost and environmental performance comparison – BDP vs. fossil based polymers. • Best alternatives mapping integrating cost and environmental performances. - Abstract: Nowadays society compels designers to develop more sustainable products. Ecodesign directs product design towards the goal of reducing environmental impacts. Within Ecodesign, materials selection plays a major role on product cost and environmental performance throughout its life cycle. This paper proposes a comprehensive life cycle framework to support Ecodesign in material selection. Dealing with new materials and technologies in early design stages, process-based models are used to represent the whole life cycle and supply integrated data to assess material alternatives, considering cost and environmental dimensions. An integrated analysis is then proposed to support decision making by mapping the best alternative materials according to the importance given to upstream and downstream life phases and to the environmental impacts. The proposed framework is applied to compare the life cycle performance of injection moulded samples made of four commercial biodegradable polymers with different contents of Thermo Plasticized Starch and PolyLactic Acid and a common fossil based polymer, Polypropylene. Instead of labelling materials just as “green”, the need to fully capture all impacts in the whole life cycle was shown. The fossil based polymer is the best economic alternative, but polymers with higher content of Thermo Plasticized Starch have a better environmental performance. However, parts geometry and EoL scenarios play a major role on the life cycle performance of candidate materials. The selection decision is then supported by mapping

  19. A Wireless Pressure Sensor Integrated with a Biodegradable Polymer Stent for Biomedical Applications.

    Science.gov (United States)

    Park, Jongsung; Kim, Ji-Kwan; Patil, Swati J; Park, Jun-Kyu; Park, SuA; Lee, Dong-Weon

    2016-06-02

    This paper describes the fabrication and characterization of a wireless pressure sensor for smart stent applications. The micromachined pressure sensor has an area of 3.13 × 3.16 mm² and is fabricated with a photosensitive SU-8 polymer. The wireless pressure sensor comprises a resonant circuit and can be used without the use of an internal power source. The capacitance variations caused by changes in the intravascular pressure shift the resonance frequency of the sensor. This change can be detected using an external antenna, thus enabling the measurement of the pressure changes inside a tube with a simple external circuit. The wireless pressure sensor is capable of measuring pressure from 0 mmHg to 230 mmHg, with a sensitivity of 0.043 MHz/mmHg. The biocompatibility of the pressure sensor was evaluated using cardiac cells isolated from neonatal rat ventricular myocytes. After inserting a metal stent integrated with the pressure sensor into a cardiovascular vessel of an animal, medical systems such as X-ray were employed to consistently monitor the condition of the blood vessel. No abnormality was found in the animal blood vessel for approximately one month. Furthermore, a biodegradable polymer (polycaprolactone) stent was fabricated with a 3D printer. The polymer stent exhibits better sensitivity degradation of the pressure sensor compared to the metal stent.

  20. A Wireless Pressure Sensor Integrated with a Biodegradable Polymer Stent for Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Jongsung Park

    2016-06-01

    Full Text Available This paper describes the fabrication and characterization of a wireless pressure sensor for smart stent applications. The micromachined pressure sensor has an area of 3.13 × 3.16 mm2 and is fabricated with a photosensitive SU-8 polymer. The wireless pressure sensor comprises a resonant circuit and can be used without the use of an internal power source. The capacitance variations caused by changes in the intravascular pressure shift the resonance frequency of the sensor. This change can be detected using an external antenna, thus enabling the measurement of the pressure changes inside a tube with a simple external circuit. The wireless pressure sensor is capable of measuring pressure from 0 mmHg to 230 mmHg, with a sensitivity of 0.043 MHz/mmHg. The biocompatibility of the pressure sensor was evaluated using cardiac cells isolated from neonatal rat ventricular myocytes. After inserting a metal stent integrated with the pressure sensor into a cardiovascular vessel of an animal, medical systems such as X-ray were employed to consistently monitor the condition of the blood vessel. No abnormality was found in the animal blood vessel for approximately one month. Furthermore, a biodegradable polymer (polycaprolactone stent was fabricated with a 3D printer. The polymer stent exhibits better sensitivity degradation of the pressure sensor compared to the metal stent.

  1. Biodegradability of PP/HMSPP and natural and synthetic polymers blends in function of gamma irradiation degradation

    Science.gov (United States)

    Cardoso, Elisabeth C. L.; Scagliusi, Sandra R.; Lima, Luis F. C. P.; Bueno, Nelson R.; Brant, Antonio J. C.; Parra, Duclerc F.; Lugão, Ademar B.

    2014-01-01

    Polymers are used for numerous applications in different industrial segments, generating enormous quantities of discarding in the environment. Polymeric materials composites account for an estimated from 20 to 30% total volume of solid waste. Polypropylene (PP) undergoes crosslinking and extensive main chain scissions when submitted to ionizing irradiation; as one of the most widely used linear hydrocarbon polymers, PP, made from cheap petrochemical feed stocks, shows easy processing leading it to a comprehensive list of finished products. Consequently, there is accumulation in the environment, at 25 million tons per year rate, since polymeric products are not easily consumed by microorganisms. PP polymers are very bio-resistant due to involvement of only carbon atoms in main chain with no hydrolysable functional group. Several possibilities have been considered to minimize the environmental impact caused by non-degradable plastics, subjecting them to: physical, chemical and biological degradation or combination of all these due to the presence of moisture, air, temperature, light, high energy radiation or microorganisms. There are three main classes of biodegradable polymers: synthetic polymers, natural polymers and blends of polymers in which one or more components are readily consumed by microorganisms. This work aims to biodegradability investigation of a PP/HMSPP (high melt strength polypropylene) blended with sugarcane bagasse, PHB (poly-hydroxy-butyrate) and PLA (poly-lactic acid), both synthetic polymers, at a 10% level, subjected to gamma radiation at 50, 100, 150 and 200 kGy doses. Characterization will comprise IR, DSC, TGA, OIT and Laboratory Soil Burial Test (LSBT).

  2. Co-delivery of daunomycin and oxaliplatin by biodegradable polymers for safer and more efficacious combination therapy.

    Science.gov (United States)

    Xiao, Haihua; Li, Wenliang; Qi, Ruogu; Yan, Lesan; Wang, Rui; Liu, Shi; Zheng, Yonghui; Xie, Zhigang; Huang, Yubin; Jing, Xiabin

    2012-11-10

    An oxaliplatin pro-drug (Oxa(IV)-COOH) with an axial carboxyl group was synthesized and conjugated to biodegradable polymers with pendant hydroxyl groups to prepare polymer-Oxa(IV) conjugates. A hydrophobic anthracycline-based drug, daunorubicin (DRB) was conjugated to similar biodegradable polymers with carboxyl groups to synthesize polymer-DRB conjugates. The two drug conjugates have the similar polymer backbone and are amphiphilic; thus, they can co-assemble into composite micelles. In the composite micelles, the polymer-Oxa(IV) conjugates can release clinically widely used water soluble anticancer drug oxaliplatin (Oxa(II)) upon reduction, while polymer-DRB conjugate is thought to release DRB via acid hydrolysis in the cancer cells. In this way, combination of the hydrophilic platinum drug Oxa(II) and hydrophobic drug DRB can be realized by delivering them in one platform. Moreover, the composite micelles showed reduced systematic toxicity and greater synergistic effect than combination of small molecules of the two anticancer drugs both in vitro and in vivo; thus, this polymer based combination therapy can be useful in future clinic application. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Implantable biodegradable polymers for IUdR radiosensitization of human glioma in vivo

    International Nuclear Information System (INIS)

    Williams, Jeffery; Dillehay, Larry; Tabassi, Kevin; Sipos, Eric; Brem, Henry

    1996-01-01

    Purpose: Halogenated pyrimidines are potentially useful for the radiosensitization of human malignant glioma. Therefore, we tested a synthetic, implantable biodegradable polymer for the controlled in vitro release of 5-iodo-2'-deoxyuridine (IUdR) and measured the resultant in vivo radiosensitization in nude mice bearing intracranial U251 human malignant glioma xenografts. Materials and Methods: In vitro: To measure release, increasing (10%, 30%, 50%) proportions of IUdR in synthetic [(poly(bis(p-carboxyphenoxy)-propane) (PCPP):sebacic acid (SA) (PCPP:SA ratio 20:80)] polymer discs were incubated in buffered physiologic saline solution. The supernatant fractions were periodically removed, replaced and assayed for IUdR. To test radiosensitization, U251 cells were incubated with or without 10 uM IUdR for 3 days followed by acute irradiation (0, 2.5, 5.0, or 10 Gy). In vivo: Polymer discs with 200 uCi of 125-IUdR were implanted intracranially in nude mice. Activity (cpm) was serially measured at specified times up to 311 hours after implantation via a collimated scintillation detector. To measure radiosensitization in vivo, mice had sequential intracranial inoculation of 2 x 10 5 U251 cells, implantation of polymer discs without (empty control) or with 50% IUdR, and radiation. We tested intensification and timing of radiation vs. timing of IUdR polymer implantation. When measured from the day of cellular inoculation, the days of implantation of empty (control) or 50% IUdR polymers and the subsequent schedules for radiation were: Expt. 1.) day 5 (5 Gy on days 7 and 8), Expt. 2.) days 4 or 7 (5 Gy on days 8 and 10), Expt. 3.) days 4 or 7 (2 Gy BID x 4 on days 7-10) and Expt. 4.) day 5 or 8 (2 Gy BID x 4 on days 8-11). Survival was measured. Results: In vitro: After 4 days the cumulative percentages of IUdR that were released were 43.7 ± 0.1, 70.0 ± 0.2, and 90.2 ± 0.2 (p 10 ) was -2.02 ± 0.02 or -3.68 ± 0.11 (p < 0.001), respectively. In vivo: The externally

  4. Polymer/hemoglobin assemblies: biodegradable oxygen carriers for artificial red blood cells.

    Science.gov (United States)

    Li, Taihang; Jing, Xiabin; Huang, Yubin

    2011-07-07

    In routine clinical procedures, blood transfusion is now suffering from the defects of the blood products, like cross-matching, short storage time and virus infection. Various blood substitutes have been designed by researchers through continual efforts. With recent progress in nanotechnology, new types of artificial red blood cells with cellular structure are available. This article aims to describe some artificial red blood cells which encapsulate or conjugate hemoglobin molecules through various approaches, especially the nanoscale self-assembly technique, to mitigate the adverse effects of free hemoglobin molecules. These types of artificial red blood cell systems, which make use of biodegradable polymers as matrix materials, show advantages over the traditional types. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Injectable and biodegradable temperature-responsive mixed polymer systems providing variable gel-forming pH regions.

    Science.gov (United States)

    Yoshida, Yasuyuki; Kawahara, Keisuke; Mitsumune, Shintaro; Kuzuya, Akinori; Ohya, Yuichi

    Aqueous solutions of biodegradable polymers exhibiting sol-to-gel transitions in response to external stimuli such as temperature and pH are expected to be used as injectable polymers (IPs) for biomedical applications. In this study, we prepared novel biodegradable temperature-responsive IP systems providing variable gel-forming pH regions. We synthesized PCGA-b-PEG-b-PCGA (tri-PCG) and attached carboxylic acid or primary amine groups on both termini, tri-PCG-COOH and tri-PCG-NH 2 , and investigated the temperature-responsive sol-to-gel transition behavior of the mixtures of these two copolymers at various pHs. We found that the gel-forming pH region of the mixed system could be easily controlled by simply changing the mixing ratios of these polymers.

  6. Effect of starch types on properties of biodegradable polymer based on thermoplastic starch process by injection molding technique

    Directory of Open Access Journals (Sweden)

    Yossathorn Tanetrungroj

    2015-04-01

    Full Text Available In this study effects of different starch types on the properties of biodegradable polymer based on thermoplastic starch (TPS were investigated. Different types of starch containing different contents of amylose and amylopectin were used, i.e. cassava starch, mungbean starch, and arrowroot starch. The TPS polymers were compounded and shaped using an internal mixer and an injection molding machine, respectively. It was found that the amount of amylose and amylopectin contents on native starch influence the properties of the TPS polymer. A high amylose starch of TPMS led to higher strength, hardness, degree of crystallization than the high amylopectin starch of TPCS. In addition, function group analysis by Fourier transforms infrared spectrophotometer, water absorption, and biodegradation by soil burial test were also examined.

  7. Assembling and properties of the polymer-particle nanostructured materials

    Science.gov (United States)

    Sheparovych, Roman

    Complementary properties of the soft and hard matter explain its common encounter in many natural and manmade applications. A combination of flexible organic macromolecules and hard mineral clusters results in new materials far advantageous than its constituents alone. In this work we study assembling of colloidal nanocrystals and polymers into complex nanostructures. Magnetism, surface wettability and adhesion comprise properties of interest for the obtained nanocomposites. Applying a magnetic field induces a reversible 1D ordering of the magnetically susceptible particles. This property was employed in the fabrication of the permanent chains of magnetite nanocrystals (d=15nm). In the assembling process the aligned particles were bound together using polyelectrolyte macromolecules. The basics of the binding process involved an electrostatic interaction between the positively charged polyelectrolyte and the negative surface of the particles (aqueous environment). Adsorption of the polymer molecules onto several adjacent particles in the aligned 1D aggregate results in the formation of the permanent particulate chains. Positive charges of the adsorbed polyelectrolyte molecules stabilize the dispersion of the obtained nanostructures in water. Magnetization measurements revealed that superparamagnetic nanoparticles, being assembled into 1D ordered structures, attain magnetic coercivity. This effect originates from the magnetostatic interaction between the neighboring magnetite nanocrystals. The preferable dipole alignment of the assembled nanoparticles is directed along the chain axis. Another system studied in this project includes polymer-particle responsive surface coatings. Tethered polymer chains and particles bearing different functionalities change surface properties upon restructuring of the composite layer. When the environment favors polymer swelling (good solvent), the polymer chains segregate to the surface and cover the particles. In the opposite case

  8. Flexible particle array structures by controlling polymer graft architecture.

    Science.gov (United States)

    Choi, Jihoon; Dong, Hongchen; Matyjaszewski, Krzysztof; Bockstaller, Michael R

    2010-09-15

    Surface-initiated atom-transfer radical polymerization is used to synthesize particle brushes with controlled fraction of extended and relaxed conformations of surface-grafted chains. In the semidilute brush limit, the grafting of polymeric ligands is shown to facilitate the formation of ordered yet plastic-compliant particle array structures in which chain entanglements give rise to fracture through a polymer-like crazing process that dramatically increases the toughness and flexibility of the particle assembly.

  9. Multi-functional particle assemblies in polymer nanocomposites

    Science.gov (United States)

    Jiao, Yang

    Self-assembly into ordered and equilibrium configurations underlie the microphase separation of block copolymers, protein folding and anisotropic aggregation of functionalized nanoparticles. In this project, we explored the assembly of polymer-grafted magnetic nanoparticles in solution and bulk states to combine various properties, such as ionic conductivity, mechanical reinforcement and responsiveness to external flows, within the same sample. The multi-functionality of iron oxide nanoparticles in polymer media is achieved using bottom-up approaches. Starting from the particle core synthesis, many layers of functionalities are added on magnetite (Fe3O4) nanoparticles by i) grafting polystyrene chains at different densities, lengths and elasticity; by ii) functionalizing particles with ionomers; and by iii) attaching charged diblock copolymers onto particles. In these three complex systems, particle nanostructures are investigated to explain the role of interactions between particle-particle, polymer-particle and polymer-polymer. We found that polystyrene-grafted Fe3O4 nanoparticles can form strings, spherical clusters and dispersed structures in polymer matrices by tuning the polymer graft density and grafted chain length. This structural transition has been explained through chain interactions and short-range dipolar interactions. We showed that chain conformation (radius of gyration) interestingly is not influenced within different dispersion states. Small-angle x-ray and neutron scattering results reveal that matrix chains do not govern the formation of strings, but have a significant impact on the size and internal structure of aggregated particles. Our findings showed that spherical aggregates of nanoparticles with low polymer graft densities are similar to interpenetrating networks in which free matrix chains bridge the fractals of particles and control the cluster density. Further, the mechanical properties of these different composite structures under

  10. Biodegradable polymer (PLGA) coatings featuring cinnamaldehyde and carvacrol mitigate biofilm formation.

    Science.gov (United States)

    Zodrow, Katherine R; Schiffman, Jessica D; Elimelech, Menachem

    2012-10-02

    Biofilm-associated infections are one of the leading causes of death in the United States. Although infections may be treated with antibiotics, the overuse of antibiotics has led to the spread of antibiotic resistance. Many natural antimicrobial compounds derived from edible plants are safe for human use and target bacteria nonspecifically. Therefore, they may impair biofilm formation with less evolutionary pressure on pathogens. Here, we explore the use of two natural antimicrobial compounds, cinnamaldehyde (CA, from cinnamon) and carvacrol (CARV, from oregano), for biofilm prevention. We have fabricated and characterized films that incorporate CA and CARV into the biodegradable, FDA-approved polymer poly(lactic-co-glycolic acid), PLGA. The addition of CA and CARV to PLGA films not only adds antimicrobial activity but also changes the surface properties of the films, making them more hydrophilic and therefore more resistant to bacterial attachment. An addition of 0.1% CA to a PLGA film significantly impairs biofilm development by Staphylococcus aureus, and 0.1% CARV in PLGA significantly decreases biofilm formation by both Escherichia coli and S. aureus. Pseudomonas aeruginosa, which is less susceptible to CA and CARV, was not affected by the addition of 0.1% CA or CARV to the PLGA coatings; however, P. aeruginosa biofilm was significantly reduced by 1.0% CA. These results indicate that both CA and CARV could potentially be used in low concentrations as natural additives in polymer coatings for indwelling devices to delay colonization by bacteria.

  11. Biodegradable poly lactone-family polymer and their applications in medical field

    International Nuclear Information System (INIS)

    Wang, S.; Bei, J.

    2005-01-01

    Poly lactone-family polymers such as poly lactide, poly glycolide and polycaprolactone are kind aliphatic polyester. Since they can degrade by hydrolysis reaction under all the ph condition and possess biocompatibility, biodegradability and other good properties, especially they included not peptide bond in their molecules, they are non-antigen and non-immunization, as well as have no-toxicity and no-stimulation. So they are interested biomaterials and very useful in medical field. However the properties of all of the homo-poly lactones can not be changed in a large range, the limited properties result in limited applications of these homo-poly lactones. Based on macromolecular design, a series of copolylactones such as poly(lactide-co-glycolide) (PLGA), poly(glycolide-co-lactide-co-caprolactone) tri- component copolymer (PGLC), tri- and multi-block poly lactide/poly(ethylene oxide) copolymer (TPLE and BPLE), as well as polycaprolactone/poly lactide/poly(ethylene oxide) copolymer (PCEL) et al were synthesized by copolymerization among various lactone monomers or lactone monomers with poly(ethylene glycol). These copolylactones have wide range of degradation life from several months to years and different mechanical properties. After plasma treatment the surface property of the copolylactones were improved further and cell affinity of the copolylactones was improved obviously. The applications of these poly lactone-family polymers in medical field for used as drug carrier in drug delivery system, and as cell scaffold in tissue engineering were discussed

  12. Arginine-based biodegradable ether-ester polymers with low cytotoxicity as potential gene carriers.

    Science.gov (United States)

    Memanishvili, Tamar; Zavradashvili, Nino; Kupatadze, Nino; Tugushi, David; Gverdtsiteli, Marekh; Torchilin, Vladimir P; Wandrey, Christine; Baldi, Lucia; Manoli, Sagar S; Katsarava, Ramaz

    2014-08-11

    The success of gene therapy depends on safe and effective gene carriers. Despite being widely used, synthetic vectors based on poly(ethylenimine) (PEI), poly(l-lysine) (PLL), or poly(l-arginine) (poly-Arg) are not yet fully satisfactory. Thus, both improvement of established carriers and creation of new synthetic vectors are necessary. A series of biodegradable arginine-based ether-ester polycations was developed, which consists of three main classes: amides, urethanes, and ureas. Compared to that of PEI, PLL, and poly-Arg, much lower cytotoxicity was achieved for the new cationic arginine-based ether-ester polymers. Even at polycation concentrations up to 2 mg/mL, no significant negative effect on cell viability was observed upon exposure of several cell lines (murine mammary carcinoma, human cervical adenocarcinoma, murine melanoma, and mouse fibroblast) to the new polymers. Interaction with plasmid DNA yielded compact and stable complexes. The results demonstrate the potential of arginine-based ether-ester polycations as nonviral carriers for gene therapy applications.

  13. Self-Rolled Porous Hollow Tubes Made up of Biodegradable Polymers.

    Science.gov (United States)

    Peng, Ling; Zhu, Jian; Agarwal, Seema

    2017-05-01

    A tubular highly porous scaffold of polylactide (PLA) and poly-ε-caprolactone (PCL) is fabricated by self-rolling of a 2D fibrous bilayer of PLA and PCL in water without use of any classical thermo-/pH-responsive polymers. The self-rolling and diameter of the tube are dependent upon the bilayer thickness and temperature. A 75 µm thick 2D bilayer (PLA = 25 µm; PCL = 50 µm) rolls to a hollow tube of diameter around 0.41 mm with multilayered wall at 40 °C within 5 min. The tubes keep their form and size in water at all temperatures once they are formed. The interesting properties of the hollow tubes, that is, permeation of gases through the walls and flow of water without leakage under tested conditions in combination with good mechanical stability, use of only biodegradable polymers, and easy and reproducible fabrication method, allow them to be promising candidates for future studies as scaffolds for tissue engineering. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Rapid prototyping of biodegradable microneedle arrays by integrating CO2 laser processing and polymer molding

    International Nuclear Information System (INIS)

    Tu, K T; Chung, C K

    2016-01-01

    An integrated technology of CO 2 laser processing and polymer molding has been demonstrated for the rapid prototyping of biodegradable poly-lactic-co-glycolic acid (PLGA) microneedle arrays. Rapid and low-cost CO 2 laser processing was used for the fabrication of a high-aspect-ratio microneedle master mold instead of conventional time-consuming and expensive photolithography and etching processes. It is crucial to use flexible polydimethylsiloxane (PDMS) to detach PLGA. However, the direct CO 2 laser-ablated PDMS could generate poor surfaces with bulges, scorches, re-solidification and shrinkage. Here, we have combined the polymethyl methacrylate (PMMA) ablation and two-step PDMS casting process to form a PDMS female microneedle mold to eliminate the problem of direct ablation. A self-assembled monolayer polyethylene glycol was coated to prevent stiction between the two PDMS layers during the peeling-off step in the PDMS-to-PDMS replication. Then the PLGA microneedle array was successfully released by bending the second-cast PDMS mold with flexibility and hydrophobic property. The depth of the polymer microneedles can range from hundreds of micrometers to millimeters. It is linked to the PMMA pattern profile and can be adjusted by CO 2 laser power and scanning speed. The proposed integration process is maskless, simple and low-cost for rapid prototyping with a reusable mold. (paper)

  15. Rapid prototyping of biodegradable microneedle arrays by integrating CO2 laser processing and polymer molding

    Science.gov (United States)

    Tu, K. T.; Chung, C. K.

    2016-06-01

    An integrated technology of CO2 laser processing and polymer molding has been demonstrated for the rapid prototyping of biodegradable poly-lactic-co-glycolic acid (PLGA) microneedle arrays. Rapid and low-cost CO2 laser processing was used for the fabrication of a high-aspect-ratio microneedle master mold instead of conventional time-consuming and expensive photolithography and etching processes. It is crucial to use flexible polydimethylsiloxane (PDMS) to detach PLGA. However, the direct CO2 laser-ablated PDMS could generate poor surfaces with bulges, scorches, re-solidification and shrinkage. Here, we have combined the polymethyl methacrylate (PMMA) ablation and two-step PDMS casting process to form a PDMS female microneedle mold to eliminate the problem of direct ablation. A self-assembled monolayer polyethylene glycol was coated to prevent stiction between the two PDMS layers during the peeling-off step in the PDMS-to-PDMS replication. Then the PLGA microneedle array was successfully released by bending the second-cast PDMS mold with flexibility and hydrophobic property. The depth of the polymer microneedles can range from hundreds of micrometers to millimeters. It is linked to the PMMA pattern profile and can be adjusted by CO2 laser power and scanning speed. The proposed integration process is maskless, simple and low-cost for rapid prototyping with a reusable mold.

  16. Biodegradability of PP/HMSPP and natural and synthetic polymers blends in function of gamma irradiation degradation

    International Nuclear Information System (INIS)

    Cardoso, Elisabeth C.L.; Scagliusi, Sandra R.; Lima, Luis F.C.P.; Bueno, Nelson R.; Brant, Antonio J.C.; Parra, Duclerc F.; Lugão, Ademar B.

    2014-01-01

    Polymers are used for numerous applications in different industrial segments, generating enormous quantities of discarding in the environment. Polymeric materials composites account for an estimated from 20 to 30% total volume of solid waste. Polypropylene (PP) undergoes crosslinking and extensive main chain scissions when submitted to ionizing irradiation; as one of the most widely used linear hydrocarbon polymers, PP, made from cheap petrochemical feed stocks, shows easy processing leading it to a comprehensive list of finished products. Consequently, there is accumulation in the environment, at 25 million tons per year rate, since polymeric products are not easily consumed by microorganisms. PP polymers are very bio-resistant due to involvement of only carbon atoms in main chain with no hydrolysable functional group. Several possibilities have been considered to minimize the environmental impact caused by non-degradable plastics, subjecting them to: physical, chemical and biological degradation or combination of all these due to the presence of moisture, air, temperature, light, high energy radiation or microorganisms. There are three main classes of biodegradable polymers: synthetic polymers, natural polymers and blends of polymers in which one or more components are readily consumed by microorganisms. This work aims to biodegradability investigation of a PP/HMSPP (high melt strength polypropylene) blended with sugarcane bagasse, PHB (poly-hydroxy-butyrate) and PLA (poly-lactic acid), both synthetic polymers, at a 10% level, subjected to gamma radiation at 50, 100, 150 and 200 kGy doses. Characterization will comprise IR, DSC, TGA, OIT and Laboratory Soil Burial Test (LSBT). - Highlights: • Polymeric materials composites account for an estimated from 20 to 30% total volume of solid waste. • Landfills will not be enough for an estimated accumulation of 25 million tons per year of plastics. • Incorporation of natural/synthetic polymers in PP/HMSPP to reduce

  17. Selenium-Substituted Hydroxyapatite/Biodegradable Polymer/Pamidronate Combined Scaffold for the Therapy of Bone Tumour

    Directory of Open Access Journals (Sweden)

    Ewa Oledzka

    2015-09-01

    Full Text Available The present study evaluated a new concept of combined scaffolds as a promising bone replacement material for patients with a bone tumour or bone metastasis. The scaffolds were composed of hydroxyapatite doped with selenium ions and a biodegradable polymer (linear or branched, and contained an active substance—bisphosphonate. For this purpose, a series of biodegradable polyesters were synthesized through a ring-opening polymerization of ε-caprolactone or d,l-lactide in the presence of 2-hydroxyethyl methacrylate (HEMA or hyperbranched 2,2-bis(hydroxymethylpropionic acid polyester-16-hydroxyl (bis-MPA initiators, substances often used in the synthesis of medical materials. The polymers were obtained with a high yield and a number-average molecular weight up to 45,300 (g/mol. The combined scaffolds were then manufactured by a direct compression of pre-synthesized hydroxyapatite doped with selenite or selenate ions, obtained polymer and pamidronate as a model drug. It was found that the kinetic release of the drug from the scaffolds tested in vitro under physiological conditions is strongly dependent on the physicochemical properties and average molecular weight of the polymers. Furthermore, there was good correlation with the hydrolytic biodegradation results of the scaffolds fabricated without drug. The preliminary findings suggest that the fabricated combined scaffolds could be effectively used for the sustained delivery of bioactive molecules at bone defect sites.

  18. Monitoring of the Enzymatically Catalyzed Degradation of Biodegradable Polymers by Means of Capacitive Field-Effect Sensors.

    Science.gov (United States)

    Schusser, Sebastian; Krischer, Maximilian; Bäcker, Matthias; Poghossian, Arshak; Wagner, Patrick; Schöning, Michael J

    2015-07-07

    Designing novel or optimizing existing biodegradable polymers for biomedical applications requires numerous tests on the effect of substances on the degradation process. In the present work, polymer-modified electrolyte-insulator-semiconductor (PMEIS) sensors have been applied for monitoring an enzymatically catalyzed degradation of polymers for the first time. The thin films of biodegradable polymer poly(D,L-lactic acid) and enzyme lipase were used as a model system. During degradation, the sensors were read-out by means of impedance spectroscopy. In order to interpret the data obtained from impedance measurements, an electrical equivalent circuit model was developed. In addition, morphological investigations of the polymer surface have been performed by means of in situ atomic force microscopy. The sensor signal change, which reflects the progress of degradation, indicates an accelerated degradation in the presence of the enzyme compared to hydrolysis in neutral pH buffer media. The degradation rate increases with increasing enzyme concentration. The obtained results demonstrate the potential of PMEIS sensors as a very promising tool for in situ and real-time monitoring of degradation of polymers.

  19. Monodisperse conjugated polymer particles by Suzuki-Miyaura dispersion polymerization.

    Science.gov (United States)

    Kuehne, Alexander J C; Gather, Malte C; Sprakel, Joris

    2012-01-01

    The self-assembly of colloidal building blocks into complex and hierarchical structures offers a versatile and powerful toolbox for the creation of new photonic and optoelectronic materials. However, well-defined and monodisperse colloids of semiconducting polymers, which would form excellent building blocks for such self-assembled materials, are not readily available. Here we report the first demonstration of a Suzuki-Miyaura dispersion polymerization; this method produces highly monodisperse submicrometer particles of a variety of semiconducting polymers. Moreover, we show that these monodisperse particles readily self-assemble into photonic crystals that exhibit a pronounced photonic stopgap.

  20. Bone formation by three-dimensional stromal osteoblast culture in biodegradable polymer scaffolds

    Science.gov (United States)

    Ishaug, S. L.; Crane, G. M.; Miller, M. J.; Yasko, A. W.; Yaszemski, M. J.; Mikos, A. G.; McIntire, L. V. (Principal Investigator)

    1997-01-01

    Bone formation was investigated in vitro by culturing stromal osteoblasts in three-dimensional (3-D), biodegradable poly(DL-lactic-co-glycolic acid) foams. Three polymer foam pore sizes, ranging from 150-300, 300-500, and 500-710 microns, and two different cell seeding densities, 6.83 x 10(5) cells/cm2 and 22.1 x 10(5) cells/cm2, were examined over a 56-day culture period. The polymer foams supported the proliferation of seeded osteoblasts as well as their differentiated function, as demonstrated by high alkaline phosphatase activity and deposition of a mineralized matrix by the cells. Cell number, alkaline phosphatase activity, and mineral deposition increased significantly over time for all the polymer foams. Osteoblast foam constructs created by seeding 6.83 x 10(5) cells/cm2 on foams with 300-500 microns pores resulted in a cell density of 4.63 x 10(5) cells/cm2 after 1 day in culture; they had alkaline phosphatase activities of 4.28 x 10(-7) and 2.91 x 10(-6) mumol/cell/min on Days 7 and 28, respectively; and they had a cell density that increased to 18.7 x 10(5) cells/cm2 by Day 56. For the same constructs, the mineralized matrix reached a maximum penetration depth of 240 microns from the top surface of the foam and a value of 0.083 mm for mineralized tissue volume per unit of cross sectional area. Seeding density was an important parameter for the constructs, but pore size over the range tested did not affect cell proliferation or function. This study suggests the feasibility of using poly(alpha-hydroxy ester) foams as scaffolding materials for the transplantation of autogenous osteoblasts to regenerate bone tissue.

  1. Methacrylated monosaccharides as the modifiers for carbochain polymers: Synthesis, mechanical/thermal properties and biodegradability of hybrids

    Science.gov (United States)

    Yakushev, P.; Bershtein, V.; Bukowska-Śluz, I.; Sobiesiak, M.; Gawdzik, B.

    2016-05-01

    Methacrylated derivatives of glucose (MGLU) and galactose (MGAL) were synthesized by the procedure described by Vogel, and their copolymers with methyl methacrylate (MMA) and MMA/N-vinyl pyrrolidone (MMA/NVP) (1:1) mixture were obtained with the aim to modify some properties of carbochain polymers, in particular to generate their biodegradability. These hybrids of synthetic and natural products, with 10, 20 or 30 wt. % modifiers, were characterized by DMA and TGA methods and in the biodegradation tests. Increasing Tg values by 20-30°C was registered in all cases whereas thermal stability was improved only for PMMA due to modification. On the contrary, only for hybrids based on hygroscopic MMA/NVP copolymer the essential biodegradability could be generated.

  2. High barrier multilayer packaging by the coextrusion method: The effect of nanocomposites and biodegradable polymers on flexible film properties

    Science.gov (United States)

    Thellen, Christopher T.

    The objective of this research was to investigate the use of nanocomposite and multilayer co-extrusion technologies for the development of high gas barrier packaging that is more environmentally friendly than many current packaging system. Co-extruded bio-based and biodegradable polymers that could be composted in a municipal landfill were one direction that this research was aimed. Down-gauging of high performance barrier films using nanocomposite technology and co-extrusion was also investigated in order to reduce the amount of solid waste being generated by the packaging. Although the research is focused on military ration packaging, the technologies could easily be introduced into the commercial flexible packaging market. Multilayer packaging consisting of poly(m-xylylene adipamide) nanocomposite layers along with adhesive and tie layers was co-extruded using both laboratory and pilot-scale film extrusion equipment. Co-extrusion of biodegradable polyhydroxyalkanoates (PHA) along with polyvinyl alcohol (PVOH) and tie layers was also accomplished using similar co-extrusion technology. All multilayer films were characterized for gas barrier, mechanical, and thermal properties. The biodegradability of the PVOH and PHA materials in a marine environment was also investigated. The research has shown that co-extrusion of these materials is possible at a research and pilot level. The use of nanocomposite poly(m-xylylene adipamide) was effective in down-gauging the un-filled barrier film to thinner structures. Bio-based PHA/PVOH films required the use of a malefic anhydride grafted PHA tie layer to improve layer to layer adhesion in the structure to avoid delamination. The PHA polymer demonstrated a high rate of biodegradability/mineralization in the marine environment while the rate of biodegradation of the PVOH polymer was slower.

  3. Biodegradable and Multifunctional Polymer Micro-Tubes for Targeting Photothermal Therapy

    Directory of Open Access Journals (Sweden)

    Xin Wang

    2014-07-01

    Full Text Available We describe an innovative form of polymer micro-tubes with diverse functions including biodegradation, magnetic manipulation, and photothermal effect that employs and activates photothermal therapy to target cancer cells. The micro-tube comprised soybean protein isolate, poly-l-glutamic acid, magnetite nanoparticles, plus gold nanoparticles. Through electrostatic force, these components, with opposite charges, formed pairs of layers in the pores of the template, various bilayers of soybean protein isolate and poly-l-glutamic acid served as the biodegradable building wall to each micro-tube. The layers of magnetite nanoparticle functionalized micro-tubes enabled the micro-tube manipulate to target the cancer cells by using an external magnetic field. The photo-thermal effect of the layer of gold nanoparticles on the outer surface of the micro-tubes, when under irradiation and when brought about by the near infrared radiation, elevated each sample’s temperature. In addition, and when under the exposure of the near infrared radiation, the elevated temperature of the suspension of the micro-tubes, likewise with a concentration of 0.2 mg/mL, and similarly with a power of 2 W and as well maintained for 10 min, elevated the temperature of the suspension beyond 42 °C. Such temperatures induced apoptosis of target cancer cells through the effect of photothermal therapy. The findings assert that structured micro-tubes have a promising application as a photothermal agent. From this assertion, the implications are that this multifunctional agent will significantly improve the methodology for cancer diagnosis and therapy.

  4. Interactions between protein coated particles and polymer surfaces studied with the rotating particles probe.

    Science.gov (United States)

    Kemper, M; Spridon, D; van IJzendoorn, L J; Prins, M W J

    2012-05-29

    Nonspecific interactions between proteins and polymer surfaces have to be minimized in order to control the performance of biosensors based on immunoassays with particle labels. In this paper we investigate these nonspecific interactions by analyzing the response of protein coated magnetic particles to a rotating magnetic field while the particles are in nanometer vicinity to a polymer surface. We use the fraction of nonrotating (bound) particles as a probe for the interaction between the particles and the surface. As a model system, we study the interaction of myoglobin coated particles with oxidized polystyrene surfaces. We measure the interaction as a function of the ionic strength of the solution, varying the oxidation time of the polystyrene and the pH of the solution. To describe the data we propose a model in which particles bind to the polymer by crossing an energy barrier. The height of this barrier depends on the ionic strength of the solution and two interaction parameters. The fraction of nonrotating particles as a function of ionic strength shows a characteristic shape that can be explained with a normal distribution of energy barrier heights. This method to determine interaction parameters paves the way for further studies to quantify the roles of protein coated particles and polymers in their mutual nonspecific interactions in different matrixes.

  5. Rotational diffusion in polymer nanocomposites as probed by anisotropic particles

    Science.gov (United States)

    Clarke, Laura

    2014-03-01

    Metal nanoparticles strongly absorb specific wavelengths of light with no (or only a very weak) radiative relaxation by which to release this energy. As a result, the absorbed energy is efficiently converted to local heat (a photothermal effect). With an effective cross-section of up to 10 times its physical size, each particle acts as a ``super-sized'' absorber even when embedded within a transparent material environment such as a polymer, resulting in dramatic heating originating at the particles. Thus, with spatially-uniform illumination, one can metaphorically reach inside a polymer nanocomposite and apply heat to pre-selected subsets (e.g., causing them to dramatically change properties due to actuation, cross-linking, crystallization, or chemical reaction) without heating the sample surface or strongly affecting the remainder of the material. By utilizing optically-accessible additives including the particles themselves, the thermal gradient from the particle outward can be experimentally determined. In particular, rotational diffusion of anisotropic particles can be used to measure the temperature at the nanoparticle, which is the warmest point in a polymeric film or nanofiber under photothermal heating. Conversely, the same technique can be utilized to measure polymer dynamics in nanocomposites in the immediate vicinity of the particle. Funding: National Science Foundation CMMI-1069108.

  6. Microencapsulation of chemotherapeutics into monodisperse and tunable biodegradable polymers via electrified liquid jets: control of size, shape, and drug release.

    Science.gov (United States)

    Fattahi, Pouria; Borhan, Ali; Abidian, Mohammad Reza

    2013-09-06

    This paper describes microencapsulation of antitumor agent 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU, Carmustine) into biodegradable polymer poly(lactic-co-glycolic) acid (PLGA) using an electrojetting technique. The resulting BCNU-loaded PLGA microcapsules have significantly higher drug encapsulation efficiency, more tunable drug loading capacity, and (3) narrower size distribution than those generated using other encapsulation methods. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. MICRON-SIZED POLYMER PARTICLES FROM TANZANIAN ...

    African Journals Online (AJOL)

    Micron sized polymeric particles were prepared from cashew nut shell liquid and subsequently functionalized to produce micron-sized carboxylated cation exchange resin (MCCER). By titrimetry and analytical procedures employing atomic absorption spectrometry, an assessment of the cation exchange capability of the ...

  8. Solution electrospinning of particle-polymer composite fibres

    DEFF Research Database (Denmark)

    Christiansen, Lasse; Fojan, Peter

    2016-01-01

    into scaffolds. The formation of a particle/polymer composite results in improved mechanical stability, without compromising the porosity. In the presented study, aerogel and poly(ethylene oxide) are mixed into a solution, and spun to thin fibres. Thereby a porous membrane, on the micro- and nano...

  9. Micron-sized polymer particles from tanzanian cashew nut shell ...

    African Journals Online (AJOL)

    Micron-sized polymer particles (MSPP) were prepared by formaldehyde condensation polymerization of cashew nut shell liquid (CNSL) previously emulsified with sodium lauryl sulphate. The sizes of the MSPP were found to range from 0.1 to 4.4 mm. Increasing the emulsifier concentration had the effect of increasing the ...

  10. Synthesis and characterization of citrate-based fluorescent small molecules and biodegradable polymers.

    Science.gov (United States)

    Xie, Zhiwei; Kim, Jimin P; Cai, Qing; Zhang, Yi; Guo, Jinshan; Dhami, Ranjodh S; Li, Li; Kong, Bin; Su, Yixue; Schug, Kevin A; Yang, Jian

    2017-03-01

    Novel citric acid based photoluminescent dyes and biodegradable polymers are synthesized via a facile "one-pot" reaction. A comprehensive understanding of the fluorescence mechanisms of the resulting citric acid-based fluorophores is reported. Two distinct types of fluorophores are identified: a thiozolopyridine family with high quantum yield, long lifetime, and exceptional photostability, and a dioxopyridine family with relatively lower quantum yield, multiple lifetimes, and solvent-dependent band shifting behavior. Applications in molecular labeling and cell imaging were demonstrated. The above discoveries contribute to the field of fluorescence chemistry and have laid a solid foundation for further development of new fluorophores and materials that show promise in a diversity of fluorescence-based applications. Photoluminescent materials are pivotal for fluorescence based imaging, labeling and sensing applications. Understanding their fluorescence mechanism is challenging and imperative. We develop a new class of citric acid-derived fluorescent materials in forms of polymers and small molecular dyes by a one-step solvent free reaction. We discovered two different classes of citric acid-derived fluorophores. A two-ring thiozolopyridine structure demonstrates strong fluorescence and exceptional resistance to photo-bleaching. A one-ring dioxopyridine exhibits relative weak fluorescence but with intriguing excitation and solvent-dependent emission wavelength shifting. Our methodology of synthesizing citric acid-derived fluorophores and the understanding on their luminescence are instrumental to the design and production of a large number of new photoluminescent materials for biological and biomedical applications. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  11. Biodegradable shape-memory polymers exhibiting sharp thermal transitions and controlled drug release.

    Science.gov (United States)

    Nagahama, Koji; Ueda, Yuichi; Ouchi, Tatsuro; Ohya, Yuichi

    2009-07-13

    Biodegradable shape-memory polymer networks prepared by cross-linking star shape branched oligo(ε-caprolactone) (bOCL) with hexamethylene diisocyanate are introduced. The thermal and mechanical properties of these networks were investigated using differential scanning calorimetry and tensile testing, respectively, and the morphology of the phase structure was characterized by polarized optical microscopy. The shape-memory properties of the networks were quantified using thermomechanical tensile experiments and showed strain fixity rates R(f) higher than 97% and strain recovery rates R(r) as high as 100%. Of note, networks of OCL segments with a lower degree of polymerization (DP; 10) exhibited significantly improved temperature-sensitive shape recovery: 90% of the permanent shape was recovered upon heating to within a 2 °C range (37-39 °C). The networks exhibited complete shape recovery to the permanent shape within 10 s at 42 °C. Theophylline-loaded (10 and 20 wt %) shape-memory materials, prepared by cross-linking bOCL with hexamethylene diisocyanate in the presence of theophylline, are also described as a model for a controlled drug release device. The 10 wt % loaded material was sufficiently soft and flexible for complex shape transformation and also showed high R(f) (98%) and R(r) (99%). Sustained release of loaded theophylline was achieved over 1 month without initial burst-release in a phosphate buffer solution (PBS; pH 7.4) at 37 °C.

  12. Design, development and optimization of oral colon targeted drug delivery system of azathioprine using biodegradable polymers.

    Science.gov (United States)

    Nath, Bipul; Nath, L K

    2013-01-01

    The present study was aimed at designing a microflora triggered colon targeted drug delivery system (MCDDS) based on swellable polysaccharide, Sterculia gum in combination with biodegradable polymers with a view to specifically deliver azathioprine in the colonic region for the treatment of IBD with reduced systemic toxicity. The microflora degradation properties of Sterculia gum was investigated in rat caecal phosphate buffer medium. The polysaccharide tablet cores were coated to different film thicknesses with blends of Eudragit RLPO and chitosan and overcoated with Eudragit L00 to provide acid and intestinal resistance. Swelling and drug release studies were carried out in simulated gastric fluid, SGF (pH 1.2), simulated intestinal fluid, SIF (pH 6.8) and simulated colonic fluid, SCF (pH 7.4 under anaerobic environment), respectively. Drug release study in SCF revealed that swelling force of the Sterculia gum could concurrently drive the drug out of the polysaccharide core due to the rupture of the chitosan/Eudargit coating in microflora activated environment. The degradation of chitosan was the rate-limiting factor for drug release in the colon. Drug release from the MCDDS was directly proportional to the concentration of the pore former (chitosan), but inversely related to the Eudragit RLPO coating thickness.

  13. Comparison between biodegradable polymers from cassava starch and glycerol as additives to biogas production

    Directory of Open Access Journals (Sweden)

    Paulo André Cremonez

    2016-08-01

    Full Text Available In this study, we compared cassava starch-based biodegradable polymers (PBMs and glycerol (G as additives used to increase biogas production from the co-digestion of swine wastewater (ARS. We chose to work with an inoculum comprising 40% (v/v of the total volume of the reactor; this inoculum was obtained from a Canadian model digester for treating swine waste. In the anaerobic digestion process, batch reactors were used on a laboratory scale with a total volume of approximately 4 L and a working volume of 3.2 L. Three treatments were conducted to compare the efficiency of solid removal, the chemical oxygen demand (COD, and the production of biogas. The first treatment contained only swine waste; the second included the addition of glycerol at 1, 3, and 5% (w/v; and the third treatment included the addition of 1, 3, and 5% (w/v of PBM residue in relation to the swine wastewater. From the results, it can be concluded that higher yields were obtained for the treatment with 3% PBM and 1% glycerol. Most treatments showed high removal rates of total solids and total volatile solids. Reductions lower than 70% were obtained only for treatments with PBM and glycerol at a ratio of 5%.

  14. Biodegradation of naphthalenesulphonate polymers: the potential of a combined application of fungi and bacteria.

    Science.gov (United States)

    Gullotto, Antonella; Lubello, Claudio; Mannucci, Alberto; Gori, Riccardo; Munz, Giulio; Briganti, Fabrizio

    2015-01-01

    The potential of several fungi and their synergy with bacterial biomasses were evaluated as a solution for the removal of 2-naphthalensulphonic acid polymers (2-NSAPs) from petrochemical wastewater, characterized by a chemical oxygen demand (COD) greater than 9000 mg/L. The ability of fungi to grow on 2-NSAP mixtures was preliminarily investigated using a solid medium, and then the action of the selected strains, both in suspended and immobilized form, was evaluated in terms of degradation, depolymerization, sorption and an increase in biodegradability of 2-NSAP. Among the 25 fungi evaluated two, in particular, Bjerkandera adusta and Pleurotus ostreatus, have been found to significantly depolymerize 2-NSAP yielding to the corresponding monomer (2-naphthalenesulphonic acid, 2-NSA), which has been further degraded by a bacterial consortia selected in a wastewater treatment plant (WWTP). The fungal treatment alone was able to reduce the COD value up to 44%, while activated sludge removed only 9% of the initial COD. In addition, the combined treatment (fungi and bacteria) allowed an increase in the COD removal up to 62%.

  15. The effect of additives interaction on the miscibility and crystal structure of two immiscible biodegradable polymers

    Directory of Open Access Journals (Sweden)

    Ahmed Mohamed El-Hadi

    2014-01-01

    Full Text Available Poly lactic acid (PLLA is a promising biopolymer, obtained from polymerization of lactic acid that is derived from renewable resources through fermentation. The characteristic brittleness of PLLA is attributed to slow crystallization rates, which results in the formation of the large spherulites. Its glass temperature is relative high, above room temperature and close to 60 ºC, and therefore its applications are limited. The additives poly((R-3-hydroxybutyrate (PHB, poly(vinyl acetate (PVAc and tributyl citrate (TBC were used as compatibilizers in the biodegradable polymer blend of (PLLA/PPC. Results from DSC and POM analysis indicated that the blends of PLLA and PPC are immiscible. However, the blends with additives are miscible. TBC as plasticizer was added to PLLA to reduce its Tg. PVAc was used as compatibilizer to improve the miscibility between PLLA and PPC. FT-IR showed about 7 cm-1 shift in the C=O peak in miscible blends due to physical interactions. POM experiments together with the results of DSC and WAXD showed that PHB enhances the crystallization behavior of PLLA by acting as bio nuclei and the crystallization process can occur more quickly. Consequently an increase was observed in the peak intensity in WAXD.

  16. Controlled release of copper from an intrauterine device using a biodegradable polymer.

    Science.gov (United States)

    Ramakrishnan, Reshmi; B, Bharaniraja; Aprem, Abi Santhosh

    2015-12-01

    The adverse effects of copper intrauterine devices (IUDs) such as abnormal bleeding, pain and cramps may be due in part to the burst release of copper ions during the first few months of usage. This study focuses on controlling the initial burst release of copper ions. This study evaluated in vitro release rates of copper for a period of 1 year from standard CuT380 IUDs (n=6) and from CuT380 IUDs coated with poly(dl-lactide-co-glycolide) (PLGA) films (n=6). This study characterized the coated device for its morphological changes during degradation of film by scanning electron microscopy (SEM). CuT380 IUDs coated with PLGA film with a thickness of 0.10±0.02 mm showed a reduced initial copper release (40-80 mcg/day) compared with uncoated CuT380 IUDs (150-200 mcg/day). Statistically significant (p<.05) results were obtained at different time intervals during the overall study period of 1 year. SEM images showed degradation of coating. Coating a CuT380 IUD with biodegradable polymer reduced the initial copper release without affecting release at 1 year. Clinical trials are required to determine whether this could reduce side effects such as bleeding and pain associated with copper containing IUDs. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Pulsed laser deposition of polyhydroxybutyrate biodegradable polymer thin films using ArF excimer laser

    Science.gov (United States)

    Kecskemeti, G.; Smausz, T.; Kresz, N.; Tóth, Zs.; Hopp, B.; Chrisey, D.; Berkesi, O.

    2006-11-01

    We demonstrated the pulsed laser deposition (PLD) of high quality films of a biodegradable polymer, the polyhydroxybutyrate (PHB). Thin films of PHB were deposited on KBr substrates and fused silica plates using an ArF ( λ = 193 nm, FWHM = 30 ns) excimer laser with fluences between 0.05 and 1.5 J cm -2. FTIR spectroscopic measurements proved that at the appropriate fluence (0.05, 0.09 and 0.12 J cm -2), the films exhibited similar functional groups with no significant laser-produced modifications present. Optical microscopic images showed that the layers were contiguous with embedded micrometer-sized grains. Ellipsometric results determined the wavelength dependence ( λ ˜ 245-1000 nm) of the refractive index and absorption coefficient which were new information about the material and were not published in the scientific literature. We believe that our deposited PHB thin films would have more possible applications. For example to our supposal the thin layers would be applicable in laser induced forward transfer (LIFT) of biological materials using them as absorbing thin films.

  18. Pulsed laser deposition of polyhydroxybutyrate biodegradable polymer thin films using ArF excimer laser

    Energy Technology Data Exchange (ETDEWEB)

    Kecskemeti, G. [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary)]. E-mail: kega@physx.u-szeged.hu; Smausz, T. [Hungarian Academy of Sciences and University of Szeged, Research Group on Laser Physics, H-6720 Szeged, Dom ter 9 (Hungary)]. E-mail: tomi@physx.u-szeged.hu; Kresz, N. [Department of Optics and Quantum Electronics, University of Szeged, H-6720 Szeged, Dom ter 9 (Hungary)]. E-mail: knr@physx.u-szeged.hu; Toth, Zs. [Hungarian Academy of Sciences and University of Szeged, Research Group on Laser Physics, H-6720 Szeged, Dom ter 9 (Hungary)]. E-mail: ztoth@physx.u-szeged.hu; Hopp, B. [Hungarian Academy of Sciences and University of Szeged, Research Group on Laser Physics, H-6720 Szeged, Dom ter 9 (Hungary)]. E-mail: bhopp@physx.u-szeged.hu; Chrisey, D. [Naval Research Laboratory, Washington, DC 20375 (United States)]. E-mail: chrisey@ccf.nrl.navy.mil; Berkesi, O. [Department of Physical Chemistry, University of Szeged, H-6720 Szeged, Rerrich B. ter 1 (Hungary)]. E-mail: oberkesi@chem.u-szeged.hu

    2006-11-30

    We demonstrated the pulsed laser deposition (PLD) of high quality films of a biodegradable polymer, the polyhydroxybutyrate (PHB). Thin films of PHB were deposited on KBr substrates and fused silica plates using an ArF ({lambda} = 193 nm, FWHM = 30 ns) excimer laser with fluences between 0.05 and 1.5 J cm{sup -2}. FTIR spectroscopic measurements proved that at the appropriate fluence (0.05, 0.09 and 0.12 J cm{sup -2}), the films exhibited similar functional groups with no significant laser-produced modifications present. Optical microscopic images showed that the layers were contiguous with embedded micrometer-sized grains. Ellipsometric results determined the wavelength dependence ({lambda} {approx} 245-1000 nm) of the refractive index and absorption coefficient which were new information about the material and were not published in the scientific literature. We believe that our deposited PHB thin films would have more possible applications. For example to our supposal the thin layers would be applicable in laser induced forward transfer (LIFT) of biological materials using them as absorbing thin films.

  19. Drug release control in delivery system for biodegradable polymer drugs by γ-radiation

    International Nuclear Information System (INIS)

    Yoshioka, Sumie; Azo, Yukio; Kojima, Shigeo

    1997-01-01

    Characterizations of the drug release from microsphere and hydrogel preparation made from biodegradable polymers were investigated aiming at development of a drug delivery system which allows an optimum drug delivery and the identification of the factors which control its delivery. Poly-lactic acid microspheres containing 10% of progesterone were produced from poly DL-lactic acid and exposed to γ-ray at 5-1000 kGy. And its glass transition temperature (Tg) was determined by differential scanning calorimetry. The temperature was gradually lowered with an increase in the dose of radiation. Tg of the microsphere exposed at 1000 kGy was lower by 10degC compared with the untreated one, showing that Tg control is possible without changing the size distribution of microsphere. Then, the amount of progesterone released from microsphere was determined. The release rate of the drug linearly increased with a square root of radiation time. These results indicate that the control of drug release rate is possible through controling the microsphere's Tg by γ-ray radiation. (M.N.)

  20. Biodegradable polymer films from seaweed polysaccharides: A review on cellulose as a reinforcement material

    Directory of Open Access Journals (Sweden)

    H. P. S. Abdul Khalil

    2017-04-01

    Full Text Available Seaweed and cellulose are promising natural polymers. This article reviews the basic information and recent developments of both seaweed and cellulose biopolymer materials as well as analyses the feasible formation of seaweed/cellulose composite films. Seaweed and cellulose both exhibit interesting film-forming properties. Nevertheless, seaweed has poor water vapour barrier and mechanical properties, whereas cellulose is neither meltable nor soluble in water or common organic solvents due to its highly crystalline structure. Therefore, modification of these hydrocolloids has been done to exploit their useful properties. Blending of biopolymers is a must recommended approach to improve the desired characteristics. From the review, seaweed is well compatible with cellulose, which possesses excellent mechanical strength and water resistance properties. Moreover, seaweed/cellulose composite films can prolong a product’s shelf life while maintaining its biodegradability. Additionally, the films show potential in contributing to the bioeconomy. In order to widen seaweed and cellulose in biocomposite application across various industries, some of the viewpoints are highlighted to be focused for future developments and applications.

  1. A Comparative Study on Immobilization of Fructosyltransferase in Biodegradable Polymers by Electrospinning.

    Science.gov (United States)

    Gabrielczyk, Jakub; Duensing, Thilo; Buchholz, Stefanie; Schwinges, Alexander; Jördening, Hans-Joachim

    2018-01-24

    Commercial application of biocatalysts depends on the efficiency of the immobilization method and residual enzyme activity. Electrospinning offers a simple and versatile route to immobilize enzymes in submicron-sized fibers and thus improved mass transfer characteristics. Performance of encapsulation of fructosyltransferase from Bacillus subtilis by emulsion, suspension, and coaxial electrospinning was compared. We particularly focused on the effect of hydrophilic properties of a set of biodegradable polymers on support's activity. Bioactivity of electrospun support in aqueous medium increased in order of the matrix hydrophilicity. Additionally, the efficiency of electrospun fibers was compared with Sepabeads®, commercial epoxy-activated resins. In fibers, enzyme loading of 68.1 mg/g and specific enzyme activity of 5.5 U/mg was achieved compared to 49.5 mg/g and 2.2 U/mg on Sepabeads. Fructosyltransferase exhibited high sensitivity towards organic solvents and covalent attachment, respectively. Immobilization of native enzyme in coaxial fibers increased the specific activity to approx. 30 U/mg which corresponds to 24% of that of the free enzyme. Finally, operational stability of fiber supports was examined in a plug-flow reactor and 5% of initial substrate conversion remained after > 2000 cycles. The efficiency of core-shell immobilizates compared to one-dimensional fibers was both in batch and continuous reaction at least 4.4-fold higher.

  2. Mass spectrometry for the elucidation of the subtle molecular structure of biodegradable polymers and their degradation products.

    Science.gov (United States)

    Kowalczuk, Marek; Adamus, Grażyna

    2016-01-01

    Contemporary reports by Polish authors on the application of mass spectrometric methods for the elucidation of the subtle molecular structure of biodegradable polymers and their degradation products will be presented. Special emphasis will be given to natural aliphatic (co)polyesters (PHA) and their synthetic analogues, formed through anionic ring-opening polymerization (ROP) of β-substituted β-lactones. Moreover, the application of MS techniques for the evaluation of the structure of biodegradable polymers obtained in ionic and coordination polymerization of cyclic ethers and esters as well as products of step-growth polymerization, in which bifunctional or multifunctional monomers react to form oligomers and eventually long chain polymers, will be discussed. Furthermore, the application of modern MS techniques for the assessment of polymer degradation products, frequently bearing characteristic end groups that can be revealed and differentiated by MS, will be discussed within the context of specific degradation pathways. Finally, recent Polish accomplishments in the area of mass spectrometry will be outlined. © 2015 Wiley Periodicals, Inc.

  3. Effect of chemical heterogeneity of biodegradable polymers on surface energy: A static contact angle analysis of polyester model films

    Energy Technology Data Exchange (ETDEWEB)

    Belibel, R.; Avramoglou, T. [INSERM U1148, Laboratory for Vascular Translational Science (LVTS), Institut Galilée, Université Paris 13, Sorbonne Paris Cité, 99 Avenue Jean-Baptiste Clément, Villetaneuse F-93430 (France); Garcia, A. [CNRS UPR 3407, Laboratoire des Sciences des Procédés et des Matériau, Institut Galilée, Université Paris 13, Sorbonne Paris Cité, 99 Avenue Jean-Baptiste Clément, Villetaneuse F-93430 (France); Barbaud, C. [INSERM U1148, Laboratory for Vascular Translational Science (LVTS), Institut Galilée, Université Paris 13, Sorbonne Paris Cité, 99 Avenue Jean-Baptiste Clément, Villetaneuse F-93430 (France); Mora, L., E-mail: Laurence.mora@univ-paris13.fr [INSERM U1148, Laboratory for Vascular Translational Science (LVTS), Institut Galilée, Université Paris 13, Sorbonne Paris Cité, 99 Avenue Jean-Baptiste Clément, Villetaneuse F-93430 (France)

    2016-02-01

    Biodegradable and bioassimilable poly((R,S)-3,3 dimethylmalic acid) (PDMMLA) derivatives were synthesized and characterized in order to develop a new coating for coronary endoprosthesis enabling the reduction of restenosis. The PDMMLA was chemically modified to form different custom groups in its side chain. Three side groups were chosen: the hexyl group for its hydrophobic nature, the carboxylic acid and alcohol groups for their acid and neutral hydrophilic character, respectively. The sessile drop method was applied to characterize the wettability of biodegradable polymer film coatings. Surface energy and components were calculated. The van Oss approach helped reach not only the dispersive and polar acid–base components of surface energy but also acid and basic components. Surface topography was quantified by atomic force microscopy (AFM) and subnanometer average values of roughness (Ra) were obtained for all the analyzed surfaces. Thus, roughness was considered to have a negligible effect on wettability measurements. In contrast, heterogeneous surfaces had to be corrected by the Cassie–Baxter equation for copolymers (10/90, 20/80 and 30/70). The impact of this correction was quantified for all the wettability parameters. Very high relative corrections (%) were found, reaching 100% for energies and 30% for contact angles. - Highlights: • We develop different polymers with various chemical compositions. • Wettability properties were calculated using Cassie corrected contact angles. • Percentage of acid groups in polymers is directly correlated to acid part of SFE. • Cassie corrections are necessary for heterogeneous polymers.

  4. Effect of chemical heterogeneity of biodegradable polymers on surface energy: A static contact angle analysis of polyester model films

    International Nuclear Information System (INIS)

    Belibel, R.; Avramoglou, T.; Garcia, A.; Barbaud, C.; Mora, L.

    2016-01-01

    Biodegradable and bioassimilable poly((R,S)-3,3 dimethylmalic acid) (PDMMLA) derivatives were synthesized and characterized in order to develop a new coating for coronary endoprosthesis enabling the reduction of restenosis. The PDMMLA was chemically modified to form different custom groups in its side chain. Three side groups were chosen: the hexyl group for its hydrophobic nature, the carboxylic acid and alcohol groups for their acid and neutral hydrophilic character, respectively. The sessile drop method was applied to characterize the wettability of biodegradable polymer film coatings. Surface energy and components were calculated. The van Oss approach helped reach not only the dispersive and polar acid–base components of surface energy but also acid and basic components. Surface topography was quantified by atomic force microscopy (AFM) and subnanometer average values of roughness (Ra) were obtained for all the analyzed surfaces. Thus, roughness was considered to have a negligible effect on wettability measurements. In contrast, heterogeneous surfaces had to be corrected by the Cassie–Baxter equation for copolymers (10/90, 20/80 and 30/70). The impact of this correction was quantified for all the wettability parameters. Very high relative corrections (%) were found, reaching 100% for energies and 30% for contact angles. - Highlights: • We develop different polymers with various chemical compositions. • Wettability properties were calculated using Cassie corrected contact angles. • Percentage of acid groups in polymers is directly correlated to acid part of SFE. • Cassie corrections are necessary for heterogeneous polymers.

  5. Effect of cross-linked biodegradable polymers on sustained release of sodium diclofenac-loaded microspheres

    Directory of Open Access Journals (Sweden)

    Avik Kumar Saha

    2013-12-01

    Full Text Available The objective of this study was to formulate an oral sustained release delivery system of sodium diclofenac(DS based on sodium alginate (SA as a hydrophilic carrier in combination with chitosan (CH and sodium carboxymethyl cellulose (SCMC as drug release modifiers to overcome the drug-related adverse effects and to improve bioavailability. Microspheres of DS were prepared using an easy method of ionotropic gelation. The prepared beads were evaluated for mean particle size, entrapment efficiency, swelling capacity, erosion and in-vitro drug release. They were also subjected to various studies such as Fourier Transform Infra-Red Spectroscopy (FTIR for drug polymer compatibility, Scanning Electron Microscopy for surface morphology, X-ray Powder Diffraction Analysis (XRD and Differential Scanning Calorimetric Analysis (DSC to determine the physical state of the drug in the beads. The addition of SCMC during the preparation of polymeric beads resulted in lower drug loading and prolonged release of the DS. The release profile of batches F5 and F6 showed a maximum drug release of 96.97 ± 0.356% after 8 h, in which drug polymer ratio was decreased. The microspheres of sodium diclofenac with the polymers were formulated successfully. Analysis of the release profiles showed that the data corresponds to the diffusion-controlled mechanism as suggested by Higuchi.

  6. Small Particle Driven Chain Disentanglements in Polymer Nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Senses, Erkan; Ansar, Siyam M.; Kitchens, Christopher L.; Mao, Yimin; Narayanan, Suresh; Natarajan, Bharath; Faraone, Antonio

    2017-04-01

    Using neutron spin-echo spectroscopy, X-ray photon correlation spectroscopy and bulk rheology, we studied the effect of particle size on the single chain dynamics, particle mobility, and bulk viscosity in athermal polyethylene oxide-gold nanoparticle composites. The results reveal an ≈ 25 % increase in the reptation tube diameter with addition of nanoparticles smaller than the entanglement mesh size (≈ 5 nm), at a volume fraction of 20 %. The tube diameter remains unchanged in the composite with larger (20 nm) nanoparticles at the same loading. In both cases, the Rouse dynamics is insensitive to particle size. These results provide a direct experimental observation of particle size driven disentanglements that can cause non-Einstein-like viscosity trends often observed in polymer nanocomposites.

  7. Formation of microscopic particles during the degradation of different polymers.

    Science.gov (United States)

    Lambert, Scott; Wagner, Martin

    2016-10-01

    This study investigated the formation and size distribution of microscopic plastic particles during the degradation of different plastic materials. Particle number concentrations in the size range 30 nm-60 μm were measured by nanoparticle tracking analysis (NTA) and Coulter Counter techniques. Each of the plastics used exhibited a measureable increase in the release of particles into the surrounding solution, with polystyrene (PS) and polylactic acid (PLA) generating the highest particle concentrations. After 112 d, particle concentrations ranged from 2147 particles ml(-1) in the control (C) to 92,465 particles ml(-1) for PS in the 2-60 μm size class; 1.2 × 10(5) particles ml(-1) (C) to 11.6 × 10(6) for PLA in the 0.6-18 μm size class; and 0.2 × 10(8) particles ml(-1) (C) to 6.4 × 10(8) particles ml(-1) for PS in the 30-2000 nm size class (84 d). A classification of samples based on principal component analysis showed a separation between the different plastic types, with PLA clustering individually in each of the three size classes. In addition, particle size distribution models were used to examine more closely the size distribution data generated by NTA. Overall, the results indicate that at the beginning of plastic weathering processes chain scission at the polymer surface causes many very small particles to be released into the surrounding solution and those concentrations may vary between plastic types. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Implant-associated local drug delivery systems based on biodegradable polymers: customized designs for different medical applications.

    Science.gov (United States)

    Sternberg, Katrin; Petersen, Svea; Grabow, Niels; Senz, Volkmar; Meyer zu Schwabedissen, Henriette; Kroemer, Heyo K; Schmitz, Klaus-Peter

    2013-10-01

    Implants providing controlled, local release of active substances are of interest in different medical applications. Therefore, the focus of the present article is the development of implant-associated diffusion- or chemically controlled local drug delivery (LDD) systems based on biodegradable polymeric drug carriers. In this context, we provide new data and review our own recently published data concerning the drug release behavior of diffusion-controlled LDD systems in relation to the kind of polymer, drug content, coating mass/thickness, and layer composition. We demonstrate that polymers allow a wide range of control over the drug release characteristics. In this regard, we show that the glass transition temperature of a polymer has an impact on its drug release. Additionally, the blending of hydrophobic, semicrystalline polymers with amorphous polymers leads to an increase in the rate of drug release compared with the pure semicrystalline polymer. Moreover, the percentage loading of the embedded drug has a considerable effect on the rate and duration of drug release. Furthermore, we discuss chemically controlled LDD systems designed for the release of biomolecules, such as growth factors, as well as nanoparticle-mediated LDD systems. With our own published data on drug-eluting stents, microstents, and cochlear implants, we highlight exemplary implant-associated LDD systems designed to improve implant performance through the reduction of undesirable effects such as in-stent restenosis and fibrosis.

  9. Matrix-assisted laser desorption/ionization mass spectrometric analysis of aliphatic biodegradable photoluminescent polymers using new ionic liquid matrices.

    Science.gov (United States)

    Serrano, Carlos A; Zhang, Yi; Yang, Jian; Schug, Kevin A

    2011-05-15

    In this study, two novel ionic liquid matrices (ILMs), N,N-diisopropylethylammonium 3-oxocoumarate and N,N-diisopropylethylammonium dihydroxymonooxoacetophenoate, were tested for the structural elucidation of recently developed aliphatic biodegradable polymers by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The polymers, formed by a condensation reaction of three components, citric acid, octane diol, and an amino acid, are fluorescent, but the exact mechanism behind their luminescent properties has not been fully elucidated. In the original studies, which introduced the polymer class (J. Yang et al., Proc. Natl. Acad. Sci. USA 2009, 106, 10086-10091), a hyper-conjugated cyclic structure was proposed as the source for the photoluminescent behavior. With the use of the two new ILMs, we present evidence that supports the presence of the proposed cyclization product. In addition, the new ILMs, when compared with a previously established ILM, N,N-diisopropylethylammonium α-cyano-3-hydroxycinnimate, provided similar signal intensities and maintained similar spectral profiles. This research also established that the new ILMs provided good spot-to-spot reproducibility and high ionization efficiency compared with corresponding crystalline matrix preparations. Many polymer features revealed through the use of the ILMs could not be observed with crystalline matrices. Ultimately, the new ILMs highlighted the composition of the synthetic polymers, as well as the loss of water that was expected for the formation of the proposed cyclic structure on the polymer backbone. Copyright © 2011 John Wiley & Sons, Ltd.

  10. Biodegradable polymer for sealing porous PEO layer on pure magnesium: An in vitro degradation study

    Energy Technology Data Exchange (ETDEWEB)

    Alabbasi, Alyaa; Mehjabeen, Afrin [Biomaterials and Engineering Materials (BEM) Laboratory, James Cook University, Townsville 4811, Queensland (Australia); Kannan, M. Bobby, E-mail: bobby.mathan@jcu.edu.au [Biomaterials and Engineering Materials (BEM) Laboratory, James Cook University, Townsville 4811, Queensland (Australia); Ye, Qingsong [Discipline of Dentistry, James Cook University, Townsville 4811, Queensland (Australia); Blawert, Carsten [Magnesium Innovation Centre, Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Geesthacht 21502 (Germany)

    2014-05-01

    Graphical abstract: - Highlights: • Poly(L-lactide) was used to seal the porous PEO layer on Mg. • The dual-layer coating improved the in vitro degradation resistance of Mg. • Localized degradation was inhibited in the dual-layer coated Mg. - Abstract: An attempt was made to seal the porous silicate-based plasma electrolytic oxidation (PEO) layer on pure magnesium (Mg) with a biodegradable polymer, poly(L-lactide) (PLLA), to delay the localized degradation of magnesium-based implants in body fluid for better in-service mechanical integrity. Firstly, a silicate-based PEO coating on pure magnesium was performed using a pulsed constant current method. In order to seal the pores in the PEO layer, PLLA was coated using a two-step spin coating method. The performance of the PEO–PLLA Mg was evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The EIS results showed that the polarization resistance (R{sub p}) of the PEO–PLLA Mg was close to two orders of magnitude higher than that of the PEO Mg. While the corrosion current density (i{sub corr}) of the pure Mg was reduced by 65% with the PEO coating, the PEO–PLLA coating reduced the i{sub corr} by almost 100%. As expected, the R{sub p} of the PEO–PLLA Mg decreased with increase in exposure time. However, it was noted that the R{sub p} of the PEO–PLLA Mg even after 100 h was six times higher than that of the PEO Mg after 48 h exposure, and did not show any visible localized attack.

  11. Biodegradable polymer nanofiber membrane for the repair of cutaneous wounds in dogs - two case reports

    Directory of Open Access Journals (Sweden)

    Lívia Gomes Amaral

    2016-12-01

    Full Text Available The study of wound healing and its treatment is extremely important in veterinary medicine due to the high frequency of wounds and the difficulty in treating wounds by second intention. Thus, the objective of this study was to evaluate the use of a nanofiber membrane made of biodegradable polymers as a method of wound treatment in dogs. This study comprised two dogs with bite wounds. Debridement and cleaning was performed followed by the application of the membrane. In one dog, the wound was in the left proximal calcaneal region with clinical signs of infection, necrotic tissue, and muscle and the gastrocnemius tendon were exposed. The wound displayed rapid formation of granulation tissue which became excessive, so it was necessary to debride several times. However, with the suspension of the use of the membrane, formation of this tissue was not observed, and the wound evolved to epithelialization and fast contraction. In the second dog, there was a deep wound on the medial aspect of the proximal right hind limb, with clinical signs of infection, with muscle exposure. Once the membrane was placed, granulation tissue formed, and the membrane was used until the level of this tissue reached the skin. The wound underwent rapid epithelialization and contraction, without developing exuberant granulation tissue. Efficient wound repair was observed and the dogs exhibited greater comfort during application and use of the membrane. More studies should be conducted in dogs focusing on the application of this membrane until the appearance of healthy granulation tissue, as continued use seems to stimulate the formation of exuberant granulation tissue.

  12. Three-dimensional culture of rat calvarial osteoblasts in porous biodegradable polymers

    Science.gov (United States)

    Ishaug-Riley, S. L.; Crane-Kruger, G. M.; Yaszemski, M. J.; Mikos, A. G.

    1998-01-01

    Neonatal rat calvarial osteoblasts were cultured in 90% porous, 75:25 poly(DL-lactic-co-glycolic acid) (PLGA) foam scaffolds for up to 56 days to examine the effects of the cell seeding density, scaffold pore size, and foam thickness on the proliferation and function of the cells in this three-dimensional environment. Osteoblasts were seeded at either 11.1 x 10(5) or 22.1 x 10(5) cells per cm2 onto PLGA scaffolds having pore sizes in the range of 150-300 or 500-710 microm with a thickness of either 1.9 or 3.2 mm. After 1 day in culture, 75.6 and 68.6% of the seeded cells attached and proliferated on the 1.9 mm thick scaffolds of 150-300 microm pore size for the low and high seeding densities, respectively. The number of osteoblasts continued to increase throughout the study and eventually leveled off near 56 days, as indicated by a quantitative DNA assay. Osteoblast/foam constructs with a low cell seeding density achieved comparable DNA content and alkaline phosphatase (ALPase) activity after 14 days, and mineralization results after 56 days to those with a high cell seeding density. A maximum penetration depth of osseous tissue of 220+/-40 microm was reached after 56 days in the osteoblast/foam constructs of 150-300 microm pore size initially seeded with a high cell density. For constructs of 500-710 microm pore size, the penetration depth was 190+/-40 microm under the same conditions. Scaffold pore size and thickness did not significantly affect the proliferation or function of osteoblasts as demonstrated by DNA content, ALPase activity, and mineralized tissue formation. These data show that comparable bone-like tissues can be engineered in vitro over a 56 day period using different rat calvarial osteoblast seeding densities onto biodegradable polymer scaffolds with pore sizes in the range of 150-710 microm. When compared with the results of a previous study where similar polymer scaffolds were seeded and cultured with marrow stromal cells, this study

  13. Modified hydrotalcite-like compounds as active fillers of biodegradable polymers for drug release and food packaging applications.

    Science.gov (United States)

    Costantino, Umberto; Nocchetti, Morena; Tammaro, Loredana; Vittoria, Vittoria

    2012-11-01

    This review treats the recent patents and related literature, mainly from the Authors laboratories, on biomedical and food packaging applications of nano-composites constituted of biodegradable polymers filled with micro or nano crystals of organically modified Layered Double Hydroxides of Hydrotalcite type. After a brief outline of the chemical and structural aspects of Hydrotalcite-like compounds (HTlc) and of their manipulation via intercalation of functional molecular anions to obtain materials for numerous, sometime unexpected applications, the review approaches the theme in three separated parts. Part 1 deals with the synthetic method used to prepare the pristine Mg-Al and Zn-Al HTlc and with the procedures of their functionalization with anti-inflammatory (diclofenac), antibacterial (chloramphenicol hemisuccinate), antifibrinolytic (tranexamic acid) drugs and with benzoates with antimicrobial activity. Procedures used to form (nano) composites of polycaprolactone, used as an example of biodegradable polymer, and functionalized HTlc are also reported. Part 2 discusses a patent and related papers on the preparation and biomedical use of a controlled delivery system of the above mentioned pharmacologically active substances. After an introduction dealing with the recent progress in the field of local drug delivery systems, the chemical and structural aspects of the patented system constituted of a biodegradable polymer and HTlc loaded with the active substances will be presented together with an extensive discussion of the drug release in physiological medium. Part 3 deals with a recent patent and related papers on chemical, structural and release property of antimicrobial species of polymeric films containing antimicrobial loaded HTlc able to act as active packaging for food products prolonging their shelf life.

  14. Particle localization and hyperuniformity of polymer-grafted nanoparticle materials

    International Nuclear Information System (INIS)

    Chremos, Alexandros; Douglas, Jack F.

    2017-01-01

    The properties of materials largely reflect the degree and character of the localization of the molecules comprising them so that the study and characterization of particle localization has central significance in both fundamental science and material design. Soft materials are often comprised of deformable molecules and many of their unique properties derive from the distinct nature of particle localization. We study localization in a model material composed of soft particles, hard nanoparticles with grafted layers of polymers, where the molecular characteristics of the grafted layers allow us to ''tune'' the softness of their interactions. Soft particles are particular interesting because spatial localization can occur such that density fluctuations on large length scales are suppressed, while the material is disordered at intermediate length scales; such materials are called ''disordered hyperuniform''. We use molecular dynamics simulation to study a liquid composed of polymer-grafted nanoparticles (GNP), which exhibit a reversible self-assembly into dynamic polymeric GNP structures below a temperature threshold, suggesting a liquid-gel transition. We calculate a number of spatial and temporal correlations and we find a significant suppression of density fluctuations upon cooling at large length scales, making these materials promising for the practical fabrication of ''hyperuniform'' materials. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Biodegradable multiblock polymers based on N-(2-hydroxypropyl)methacrylamide designed as drug carriers for tumor-targeted delivery

    Czech Academy of Sciences Publication Activity Database

    Mužíková, Gabriela; Pola, Robert; Laga, Richard; Pechar, Michal

    2016-01-01

    Roč. 217, č. 15 (2016), s. 1690-1703 ISSN 1022-1352 R&D Projects: GA ČR(CZ) GA14-12742S; GA ČR(CZ) GA16-17207S; GA MŠk(CZ) LO1507; GA MŠk(CZ) LQ1604; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61389013 Keywords : biodegradable polymers * click chemistry * drug delivery systems Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.500, year: 2016

  16. Cytocompatibility of novel extracellular matrix protein analogs of biodegradable polyester polymers derived from α-hydroxy amino acids.

    Science.gov (United States)

    Lecht, Shimon; Cohen-Arazi, Naomi; Cohen, Gadi; Ettinger, Keren; Momic, Tatjana; Kolitz, Michal; Naamneh, Majdi; Katzhendler, Jehoshua; Domb, Abraham J; Lazarovici, Philip; Lelkes, Peter I

    2014-01-01

    One of the challenges in regenerative medicine is the development of novel biodegradable materials to build scaffolds that will support multiple cell types for tissue engineering. Here we describe the preparation, characterization, and cytocompatibility of homo- and hetero-polyesters of α-hydroxy amino acid derivatives with or without lactic acid conjugation. The polymers were prepared by a direct condensation method and characterized using gel permeation chromatography, (1)H-nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, optical activity, and solubility. The surface charge of the polymers was evaluated using zeta potential measurements. The polymers were coated onto glass cover slips followed by characterization using nano-surface profiler, thin film reflectometry, and atomic force microscopy (AFM). Their interaction with endothelial and neuronal cells was assessed using adhesion, proliferation, and differentiation assays. Of the characterized polymers, Poly-HOVal-LA, but not Poly-(D)HOPhe, significantly augmented nerve growth factor (NGF)-induced neuronal differentiation of the PC12 pheochromcytoma cells. In contrast, Poly-HOLeu increased by 20% the adhesion of endothelial cells, but did not affect PC12 cell differentiation. NGF-induced Erk1/2 phosphorylation in PC12 cells grown on the different polymers was similar to the effect observed for cells cultured on collagen type I. While no significant association could be established between charge and the differentiative/proliferative properties of the polymers, AFM analysis indicated augmentation of NGF-induced neuronal differentiation on smooth polymer surfaces. We conclude that overall selective cytocompatibility and bioactivity might render α-hydroxy amino acid polymers useful as extracellular matrix-mimicking materials for tissue engineering.

  17. Effective delivery of siRNA into cancer cells and tumors using well-defined biodegradable cationic star polymers.

    Science.gov (United States)

    Boyer, Cyrille; Teo, Joann; Phillips, Phoebe; Erlich, Rafael B; Sagnella, Sharon; Sharbeen, George; Dwarte, Tanya; Duong, Hien T T; Goldstein, David; Davis, Thomas P; Kavallaris, Maria; McCarroll, Joshua

    2013-06-03

    Cancer is one of the most common causes of death worldwide. Two types of cancer that have high mortality rates are pancreatic and lung cancer. Despite improvements in treatment strategies, resistance to chemotherapy and the presence of metastases are common. Therefore, novel therapies which target and silence genes involved in regulating these processes are required. Short-interfering RNA (siRNA) holds great promise as a therapeutic to silence disease-causing genes. However, siRNA requires a delivery vehicle to enter the cell to allow it to silence its target gene. Herein, we report on the design and synthesis of cationic star polymers as novel delivery vehicles for siRNA to silence genes in pancreatic and lung cancer cells. Dimethylaminoethyl methacrylate (DMAEMA) was polymerized via reversible addition-fragmentation transfer polymerization (RAFT) and then chain extended in the presence of both cross-linkers N,N-bis(acryloyl)cistamine and DMAEMA, yielding biodegradable well-defined star polymers. The star polymers were characterized by transmission electron microscopy, dynamic light scattering, ζ potential, and gel permeation chromatography. Importantly, the star polymers were able to self-assemble with siRNA and form small uniform nanoparticle complexes. Moreover, the ratios of star polymer required to complex siRNA were nontoxic in both pancreatic and lung cancer cells. Treatment with star polymer-siRNA complexes resulted in uptake of siRNA into both cell lines and a significant decrease in target gene mRNA and protein levels. In addition, delivery of clinically relevant amounts of siRNA complexed to the star polymer were able to silence target gene expression by 50% in an in vivo tumor setting. Collectively, these results provide the first evidence of well-defined small cationic star polymers to deliver active siRNA to both pancreatic and lung cancer cells and may be a valuable tool to inhibit key genes involved in promoting chemotherapy drug resistance and

  18. Synthesis of biodegradable amphiphilic Y-shaped block co-polymers via ring-opening polymerization for drug delivery.

    Science.gov (United States)

    Jia, Lin; Yan, Lifeng; Li, Yang

    2011-01-01

    A series of novel Y-shaped biodegradable block co-polymers of poly(ε-caprolactone) (PCL) and poly(ethyl ethylene phosphate) (PEEP) (PCL-(PEEP)2) were synthesized via ring-opening polymerization (ROP) of EEP with bis-hydroxy-functional ROP initiator (init-PCL-(OH)2). The init-PCL-(OH)2 was synthesized by ROP of CL using 4-hydroxybutyl acrylate (HBA) as initiator and L-tartaric acid as catalyst in bulk, and subsequently the resulting vinyl-terminated PCL was end-capped by acetyl chloride, followed by Michael addition using excess diethanolamine. The Y-shaped co-polymers and their intermediates were characterized by (1)H-, (13)C-, (31)P-NMR, FT-IR and gel-permeation chromatography. The results indicated that the molecular weight of the Y-shaped co-polymers increased with the increasing of the molar ratios of EEP to init-PCL-(OH)2 in the feed, while the PCL chain length was kept constant. The amphiphilic block co-polymers could self-assemble into micelles in aqueous solution, which was demonstrated by dynamic light scattering, (1)H-NMR and atomic force microscopy. A study of controlled release of indomethacin indicated that the amphiphilic block co-polymers could potentially provide novel vehicles for drug delivery.

  19. Full-scale performance of selected starch-based biodegradable polymers in sludge dewatering and recommendation for applications.

    Science.gov (United States)

    Zhou, Kuangxin; Stüber, Johan; Schubert, Rabea-Luisa; Kabbe, Christian; Barjenbruch, Matthias

    2018-01-01

    Agricultural reuse of dewatered sludge is a valid route for sludge valorization for small and mid-size wastewater treatment plants (WWTPs) due to the direct utilization of nutrients. A more stringent of German fertilizer ordinance requires the degradation of 20% of the synthetic additives like polymeric substance within two years, which came into force on 1 January 2017. This study assessed the use of starch-based polymers for full-scale dewatering of municipal sewage sludge. The laboratory-scale and pilot-scale trials paved the way for full-scale trials at three WWTPs in Germany. The general feasibility of applying starch-based 'green' polymers in full-scale centrifugation was demonstrated. Depending on the sludge type and the process used, the substitution potential was up to 70%. Substitution of 20-30% of the polyacrylamide (PAM)-based polymer was shown to achieve similar total solids (TS) of the dewatered sludge. Optimization of operational parameters as well as machinery set up in WWTPs is recommended in order to improve the shear stability force of sludge flocs and to achieve higher substitution potential. This study suggests that starch-based biodegradable polymers have great potential as alternatives to synthetic polymers in sludge dewatering.

  20. Development of biodegradable metaloxide/polymer nanocomposite films based on poly-ε-caprolactone and terephthalic acid.

    Science.gov (United States)

    Varaprasad, Kokkarachedu; Pariguana, Manuel; Raghavendra, Gownolla Malegowd; Jayaramudu, Tippabattini; Sadiku, Emmanuel Rotimi

    2017-01-01

    The present investigation describes the development of metal-oxide polymer nanocomposite films from biodegradable poly-ε-caprolactone, disposed poly(ethylene terephthalate) oil bottles monomer and zinc oxide-copper oxide nanoparticles. The terephthalic acid and zinc oxide-copper oxide nanoparticles were synthesized by using a temperature-dependent precipitation technique and double precipitation method, respectively. The terephthalic acid synthesized was confirmed by FTIR analysis and furthermore, it was characterized by thermal analysis. The as-prepared CuO-ZnO nanoparticles structure was confirmed by XRD analysis and its morphology was analyzed by SEM/EDS and TEM. Furthermore, the metal-oxide polymer nanocomposite films have excellent mechanical properties, with tensile strength and modulus better than pure films. The metal-oxide polymer nanocomposite films that were successfully developed show a relatively brighter colour when compared to CuO film. These new metal-oxide polymer nanocomposite films can replace many non-degradable plastics. The new metal-oxide polymer nanocomposite films developed are envisaged to be suitable for use in industrial and domestic packaging applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Synthesis, properties and applications of biodegradable polymers derived from diols and dicarboxylic acids: from polyesters to poly(ester amide)s.

    Science.gov (United States)

    Díaz, Angélica; Katsarava, Ramaz; Puiggalí, Jordi

    2014-04-25

    Poly(alkylene dicarboxylate)s constitute a family of biodegradable polymers with increasing interest for both commodity and speciality applications. Most of these polymers can be prepared from biobased diols and dicarboxylic acids such as 1,4-butanediol, succinic acid and carbohydrates. This review provides a current status report concerning synthesis, biodegradation and applications of a series of polymers that cover a wide range of properties, namely, materials from elastomeric to rigid characteristics that are suitable for applications such as hydrogels, soft tissue engineering, drug delivery systems and liquid crystals. Finally, the incorporation of aromatic units and α-amino acids is considered since stiffness of molecular chains and intermolecular interactions can be drastically changed. In fact, poly(ester amide)s derived from naturally occurring amino acids offer great possibilities as biodegradable materials for biomedical applications which are also extensively discussed.

  2. Synthesis, Properties and Applications of Biodegradable Polymers Derived from Diols and Dicarboxylic Acids: From Polyesters to Poly(ester amide)s

    Science.gov (United States)

    Díaz, Angélica; Katsarava, Ramaz; Puiggalí, Jordi

    2014-01-01

    Poly(alkylene dicarboxylate)s constitute a family of biodegradable polymers with increasing interest for both commodity and speciality applications. Most of these polymers can be prepared from biobased diols and dicarboxylic acids such as 1,4-butanediol, succinic acid and carbohydrates. This review provides a current status report concerning synthesis, biodegradation and applications of a series of polymers that cover a wide range of properties, namely, materials from elastomeric to rigid characteristics that are suitable for applications such as hydrogels, soft tissue engineering, drug delivery systems and liquid crystals. Finally, the incorporation of aromatic units and α-amino acids is considered since stiffness of molecular chains and intermolecular interactions can be drastically changed. In fact, poly(ester amide)s derived from naturally occurring amino acids offer great possibilities as biodegradable materials for biomedical applications which are also extensively discussed. PMID:24776758

  3. METHOD FOR PROVIDING SHAPED BIODEGRADABLE AND ELASTOMERIC STRUCTURES OF (CO) POLYMERS OF 1,3-TRIMETHYLENE CARBONATE (TMC), SHAPED BIODEGRADABLE AND ELASTOMERIC STRUCTURES, AND THE USE OF THESE STRUCTURES

    NARCIS (Netherlands)

    Grijpma, D.W.; Pêgo, A.P.; Feijen, Jan

    2004-01-01

    The present invention relates to methods for providing shaped biodegradable and elastomeric structures of (co)polymers of 1,3­trimethylene carbonate (TMC) with improved (mechanical) properties which can be used for tissue or tissue component support, generation or regeneration. Such shaped

  4. In vitro degradation of biodegradable polylactic acid/magnesium composites: Relevance of Mg particle shape.

    Science.gov (United States)

    Cifuentes, S C; Gavilán, R; Lieblich, M; Benavente, R; González-Carrasco, J L

    2016-03-01

    Absorbable medical devices must be developed in order to have an appropriate degradation rate in agreement with the healing rate of bone in the implantation site. In this work, biodegradable composites formed by a polylactic acid matrix reinforced with 10%wt. magnesium microparticles were processed and their in vitro degradation investigated during 28 days. A joint analysis of the amount of H2 released, the changes in pH in buffered (PBS) and non-buffered media (distilled water), the variations in mass, microstructure and the mechanical performance of the specimens was developed. The main aim was to elucidate the relevance of Mg particles shape on tailoring the degradation kinetics of these novel composites. The results show that the shape of the Mg reinforcing particles plays a crucial role in the degradation rate of PLA/Mg composites, with spherical particles promoting a lower degradation rate than irregular particles. This fact is only partially due to the smaller surface area to volume ratio of the spherical particles. Irregular particles promote a faster formation of cracks and, therefore, an increasingly faster degradation of the polymeric matrix. In every case, the amount of H2 released by the composites was well below that released by monolithic Mg. The pH of PBS during degradation remained always within 7.2 and 7.4. PLA/Mg reinforced with spherical particles retains more than 90% of its mechanical properties after 7 days of immersion and more than 60% after 28 days. The increasing demand for temporary orthopaedic implants is the driving force to seek new strategies to decrease costs and simultaneously improve patients comfort as well as simplify surgical procedures. Resorbable medical devices must be developed in order to have an appropriate degradation rate in agreement with the healing rate of bone. We are presenting for the first time results of the degradation kinetics of a new material based on polylactic acid reinforced with 10%wt. Mg microparticles

  5. Interaction of energetic particles with polymer surfaces: surface morphology development and sputtered polymer-fragment ion analysis

    International Nuclear Information System (INIS)

    Michael, R.S.

    1987-01-01

    The core of this thesis is based on a series of papers that have been published or will soon be published in which the various processes taking place in the energetic particle-polymer surface interaction scene is investigated. Results presented show different developments on polymer surfaces when compared to the vast experimental data on energetic particle-metal surface interactions. The surface morphology development depends on the physical characteristics of the polymer. Sputtering yields of fluoropolymers were several orders higher than the sputtering yields of aliphatic and aromatic polymers. Depending on the chemical nature of the polymer, the surface morphology development was dependent upon the extent of radiation-damage accumulation. Fast Atom Bombardment Mass Spectrometry at low and high resolution was applied to the characterization of sputtered polymer fragment ions. Fragment ions and their intensities were used to identify polymer samples, observe radiation damage accumulation and probe polymer-polymer interface of a polymer-polymer sandwich structure. A model was proposed which attempts to explain the nature of processes involved in the energetic particle-polymer surface interaction region

  6. TGF-beta1 release from biodegradable polymer microparticles: its effects on marrow stromal osteoblast function

    Science.gov (United States)

    Lu, L.; Yaszemski, M. J.; Mikos, A. G.; McIntire, L. V. (Principal Investigator)

    2001-01-01

    BACKGROUND: Controlled release of transforming growth factor-beta1 (TGF-beta1) to a bone defect may be beneficial for the induction of a bone regeneration cascade. The objectives of this work were to assess the feasibility of using biodegradable polymer microparticles as carriers for controlled TGF-beta1 delivery and the effects of released TGF-beta1 on the proliferation and differentiation of marrow stromal cells in vitro. METHODS: Recombinant human TGF-beta1 was incorporated into microparticles of blends of poly(DL-lactic-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG). Fluorescein isothiocynate-labeled bovine serum albumin (FITC-BSA) was co-encapsulated as a porogen. The effects of PEG content (0, 1, or 5% by weight [wt%]) and buffer pH (3, 5, or 7.4) on the protein release kinetics and the degradation of PLGA were determined in vitro for as long as 28 days. Rat marrow stromal cells were seeded on a biodegradable poly(propylene fumarate) (PPF) substrate. The dose response and biological activity of released TGF-beta1 was determined after 3 days in culture. The effects of TGF-beta1 released from PLGA/PEG microparticles on marrow stromal cell proliferation and osteoblastic differentiation were assessed during a 21-day period. RESULTS: TGF-beta1 was encapsulated along with FITC-BSA into PLGA/PEG blend microparticles and released in a multiphasic fashion including an initial burst for as long as 28 days in vitro. Increasing the initial PEG content resulted in a decreased cumulative mass of released proteins. Aggregation of FITC-BSA occurred at lower buffer pH, which led to decreased release rates of both proteins. The degradation of PLGA was increased at higher PEG content and significantly accelerated at acidic pH conditions. Rat marrow stromal cells cultured on PPF substrates showed a dose response to TGF-beta1 released from the microparticles similar to that of added TGF-beta1, indicating that the activity of TGF-beta1 was retained during microparticle

  7. Polymer degradation and ultrafine particles: Potential inhalation hazards for astronauts

    Science.gov (United States)

    Ferin, J.; Oberdörster, G.

    When Teflon is heated the developing fumes produce in exposed humans an influenza-like syndrome (polymer fume fever) or also severe toxic effects like pulmonary edema, pneumonitis and death. The decomposition products and the resulting health effects are temperature-dependent. The toxic effects seem to be related to the ultrafine particulate fraction of the fume. To test the hypothesis that exposure to ultrafine particles results in an increased interstitialization of the particles which is accompanied by an acute pathological inflammation, rats were exposed to titanium dioxide (TiO 2) particles by intratracheal instillation and by inhalation. Both acute intratracheal instillation and subchronic inhalation studies on rats show that ultrafine TiO 2 particles (˜20 nm diameter) access the pulmonary interstitium to a larger extent than fine particles (˜250 nm diameter) and that they elicit an inflammatory response as indicated by PMN increase in lavaged cells. The release of ultrafine particles into the air of an enclosed environment from a thermodegradation event or from other sources is a potential hazard for astronauts. Knowing the mechanisms of action is a prerequisite for technical or medical countermeasures.

  8. Low Density Polyethylene (LDPE blends based on Poly(3-Hydroxi-Butyrate (PHB and Guar Gum (GG biodegradable polymers

    Directory of Open Access Journals (Sweden)

    Marisa Cristina Guimarães Rocha

    2015-02-01

    Full Text Available LDPE blends based on PHB and GG biodegradable polymers were prepared by melt mixing in a twin screw extruder. The mechanical properties of the materials were evaluated. Preliminary information about the biodegradation behavior of the specimens was obtained by visual observation of samples removed from the simulated soil in 90 days. The results indicated that LDPE/PHB blends may be used for designing LDPE based materials with increased susceptibility to degradation, if elongation at break and impact properties are not determinant factors of their performance. LDPE based materials on GG present values of flexural and mechanical strength lower than those of LDPE/PHB blends. LDPE/PHB/GG blends exhibit unsatisfactory properties. Apparently, the effect of addition of GG to LDPE on the biodegradation behavior of LDPE/GG blends was less intense than the effect caused by addition of PHB to the blends. Similar observation has occurred with the partial replacement of GG by PHB in the ternary blends.

  9. Endothelial Barrier Protein Expression in Biodegradable Polymer Sirolimus-Eluting Versus Durable Polymer Everolimus-Eluting Metallic Stents.

    Science.gov (United States)

    Mori, Hiroyoshi; Cheng, Qi; Lutter, Christoph; Smith, Samantha; Guo, Liang; Kutyna, Matthew; Torii, Sho; Harari, Emanuel; Acampado, Eduardo; Joner, Michael; Kolodgie, Frank D; Virmani, Renu; Finn, Aloke V

    2017-12-11

    This study sought to investigate endothelial coverage and barrier protein expression following stent implantation. Biodegradable polymer drug-eluting stents (BP-DES) have been purported to have biological advantages in vessel healing versus durable polymer DES (DP-DES), although clinical trial data suggest equipoise. Biodegradable polymer-sirolimus-eluting stents (BP-SES), durable polymer-everolimus-eluting stents (DP-EES), and bare-metal stents (BMS) were compared. In the rabbit model (28, 45, and 120 days), stented arteries underwent light microscopic analysis and immunostaining for the presence of vascular endothelium (VE)-cadherin, an endothelial barrier protein, and were subjected to confocal microscopy and scanning electron microscopy. A cell culture study in stented silicone tubes was performed to assess cell proliferation. Light microscopic assessments were similar between BP-SES and DP-EES. BMS showed nearly complete expression of VE-cadherin at 28 days, whereas both DES showed significantly less with results favoring BP-SES versus DP-EES (39% coverage in BP-SES, 22% in DP-EES, 95% in BMS). Endothelial cell morphologic patterns differed according to stent type with BMS showing a spindle-like shape, DP-EES a cobblestone pattern, and BP-SES a shape in between. VE-cadherin-negative areas showed greater surface monocytes regardless of type of stent. Cell proliferation was suppressed in both DES with numerically less suppression in BP-SES versus DP-EES. This is the first study to examine VE-cadherin expression after DES. All DES demonstrated deficient barrier expression relative to BMS with results favoring BP-SES versus DP-EES. These findings may have important implications for the development of neoatherosclerosis in different stent types. Copyright © 2017 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

  10. Biodegradable polymers by reactive blending trans-esterification of thermoplastic starch with poly (vinyl acetate) and poly (vinyl acetate-co-butyl acrylate)

    CSIR Research Space (South Africa)

    Vargha, V

    2005-04-01

    Full Text Available (vinyl alcohol- co-acetate) is expected. The internally plasticized PVAC, i.e. poly(vinyl acetate-co-butyl acrylate), would serve to decrease the glass transition temperature range of the resulting blend. Both polymers are sold as biodegradable by the supplier... stream_source_info vargha_2005.pdf.txt stream_content_type text/plain stream_size 37663 Content-Encoding ISO-8859-1 stream_name vargha_2005.pdf.txt Content-Type text/plain; charset=ISO-8859-1 Biodegradable polymers...

  11. Crosslinked Functional Polymer Nanowire Formation Along Single Particle Tracks

    International Nuclear Information System (INIS)

    Tagawa, S.

    2006-01-01

    The use of high-energy charged particles has extended to many fields in recent years. In medicine, non-homogeneous energy deposition along an ion trajectory (ion track) plays a crucial role in cancer radiotherapy, allowing for high spatial selectivity in the distribution of the radiation dose. The direct observation and application of ion tracks in media have also attracted interest in materials science, where it is known as nuclear track fabrication. Since the discovery that high-energy particle leave latent tracks in inorganic and organic polymer materials, the technique has also been applied to the production of micro- and nano-sized pores in materials through chemical etching of the tracks. The clear correlation between the etched pore and the characteristics of the incident charged particle has been utilized for measurement of the velocity and mass of the incident particles, and such organic film detectors are widely used in dosimetry, and in particular for galactic cosmic rays in space. The scope of the present paper is the direct nano-structure formation based on crosslinking reactions induced in nano-scale ultra-small spaces of single particle tracks. We have developed the simple one-step formation processes of nanowires without using any chemical etching or refilling processes. The present technique is in striking contrast to the previous 'nuclear track' nanofabrication techniques. According to its high feasibility for the preparation of 1-D nanowires based on 'any' kinds of polymeric materials, the present paper demonstrates the formation of not only simple polymer nanowires but also ceramic and/or multi-segment multi-functional nanowires

  12. A Mechanistic Model for Drug Release in PLGA Biodegradable Stent Coatings Coupled with Polymer Degradation and Erosion

    Science.gov (United States)

    Zhu, Xiaoxiang; Braatz, Richard D.

    2015-01-01

    Biodegradable poly(D,L-lactic-co-glycolic acid) (PLGA) coating for applications in drug-eluting stents has been receiving increasing interest as a result of its unique properties compared with biodurable polymers in delivering drug for reducing stents-related side effects. In this work, a mathematical model for describing the PLGA degradation and erosion and coupled drug release from PLGA stent coating is developed and validated. An analytical expression is derived for PLGA mass loss that predicts multiple experimental studies in the literature. An analytical model for the change of the number-average degree of polymerization (or molecular weight) is also derived. The drug transport model incorporates simultaneous drug diffusion through both the polymer solid and the liquid-filled pores in the coating, where an effective drug diffusivity model is derived taking into account factors including polymer molecular weight change, stent coating porosity change, and drug partitioning between solid and aqueous phases. The model is used to describe in vitro sirolimus release from PLGA stent coating, and demonstrates the significance of simultaneous sirolimus release via diffusion through both polymer solid and pore space. The proposed model is compared to existing drug transport models, and the impact of model parameters, limitations and possible extensions of the model are also discussed. PMID:25345656

  13. Theoretical study on modeling and prediction of optical rotation for biodegradable polymers containing α-amino acids using QSAR approaches.

    Science.gov (United States)

    Mallakpour, Shadpour; Hatami, Mehdi; Golmohammadi, Hassan

    2011-07-01

    The main purpose of the present study was modeling and prediction of the optical rotation ([M](D)) of some biodegradable polymers containing α-amino acids using quantitative structure-activity relationship (QSAR) approaches. In order to attain this goal, the optical rotation of a collection of 53 polymers was selected as a data set. The data set was randomly divided into three sections, training, test and external validation sets. By using dragon software, various descriptors were calculated for all molecules in the data set. The important descriptors were selected applying genetic algorithm-partial least squares (GA-PLS) method. Then an artificial neural network (ANN) was written with MATLAB 7 and used these descriptors as inputs and its output was optical rotation of desired polymers. Then, the constructed network was used for the prediction of ([M](D)) values of validation set. The squared correlation coefficient R² values of the ANN model for the training, test and validation sets were 0.998, 0.996 and 0.996 respectively. The results showed the ability of developed ANN to predict optical rotation of various polymers.

  14. Early vascular healing with rapid breakdown biodegradable polymer sirolimus-eluting versus durable polymer everolimus-eluting stents assessed by optical coherence tomography

    Energy Technology Data Exchange (ETDEWEB)

    Tada, Tomohisa, E-mail: tomohisa@dhm.mhn.de [Deutsches Herzzentrum, Technische Universität, München (Germany); Byrne, Robert A. [Deutsches Herzzentrum, Technische Universität, München (Germany); Schuster, Tibor [Institut für Medizinische Statistik und Epidemiologie, München (Germany); Cuni, Rezarta [Deutsches Herzzentrum, Technische Universität, München (Germany); Kitabata, Hironori [Wakayama Medical University, Wakayama (Japan); Tiroch, Klaus [Deutsches Herzzentrum, Technische Universität, München (Germany); Dirninger, Alfred; Gratze, Franz; Kaspar, Klaus; Zenker, Gerald [Landeskrankenhaus Bruck/Mur (Austria); Joner, Michael; Schömig, Albert; Kastrati, Adnan [Deutsches Herzzentrum, Technische Universität, München (Germany)

    2013-03-15

    Background: Differences in early arterial healing patterns after stent implantation between biodegradable and durable polymer based new generation drug-eluting stents are not well understood. The aim of this study was to compare the healing patterns of a novel rapid breakdown (≤ 8 weeks) biodegradable polymer sirolimus-eluting stent (BP-SES) with a durable polymer everolimus-eluting stent (EES) using intravascular optical coherence tomography (OCT) at 4 months. Methods: A total of 20 patients were randomly assigned to stenting with BP-SES (n = 11) or EES (n = 9). Overall intravascular imaging was available for 15 (75%) patients. The primary endpoint was the difference in rate of uncovered struts between BP-SES and EES. To account for strut-level clustering, the results in both treatment groups were compared using a generalized linear mixed model approach. Results: Regarding the primary endpoint, BP-SES as compared to EES showed similar rates of uncovered struts (37 [6.8%] versus 167 [17.5%], odds ratio (OR) 0.45 (95% CI 0.09-2.24), p = 0.33). There were no malapposed struts in BP-SES group and 14 malapposed struts in EES group (p = 0.97). No difference in percent neointimal volume (14.1 ± 8.2% vs. 11.4 ± 6.4%, p = 0.56) was observed. Conclusions: Although rapid-breakdown BP-SES as compared to EES showed signs of improved early tissue coverage, after adjustment for strut-level clustering these differences were not statistically significant. No differences in ability to suppress neointimal hyperplasia after stent implantation between 2 stents were observed.

  15. Development of biodegradable scaffolds based on magnetically guided assembly of magnetic sugar particles.

    Science.gov (United States)

    Hu, Chengzhi; Uchida, Tomoyuki; Tercero, Carlos; Ikeda, Seiichi; Ooe, Katsutoshi; Fukuda, Toshio; Arai, Fumihito; Negoro, Makoto; Kwon, Guiryong

    2012-05-31

    Biodegradable scaffolds with controlled pore layout and porosity have great significance in tissue engineering for cell penetration, tissue ingrowth, vascularization, and nutrient delivery. Porogen leaching has been commonly used to control pore size, pore structure and porosity in the scaffold. In this paper we focus on the use/development of two magnetically guided porogen assembly methods using magnetic sugar particles (MSPs) for scaffold fabrication. First, a patterning device is utilized to align MSPs following designed templates. Then a magnetic sheet film is fabricated by mixing poly(vinyl alcohol, PVA) and NdFeB powder for steering the MSPs. After poly(l-lactide-co-ɛ-caprolactone) (PLCL) casting and removal of the sugar template, a scaffold with spherical pores is obtained. The surface and the inner structure of the scaffolds are evaluated using light and electron micrographs showing their interconnection of pores, pore wall morphology and porosity. Single layer scaffolds with the size of 8mm in width and 10mm in length were constructed with controllable pore diameters in the ranges of 105-150 μm, 250-300 μm and 425-500 μm. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. Anaerobic biodegradation of a petrochemical waste-water using biomass support particles

    International Nuclear Information System (INIS)

    Sharma, S.; Ramakrishna, C.; Desai, J.D.; Bhatt, N.M.

    1994-01-01

    During the anaerobic biodegradation of effluent from a dimethyl terephthalate (DMT) manufacturing plant, reduction in chemical oxygen demand (COD) degradation and biogas formation was observed after the waste-water concentration exceeded 25% of added feed COD. This condition reverted back to normal after 25-30 days when the DMT waste-water concentration in the feed was brought down to a non-toxic level. However, the above effects were observed only after the concentration of DMT waste-water reached more than 75% of added feed COD when biomass support particles (BSP) were augmented to the system. In the BSP system, a biomass concentration of up to 7000 mg/l was retained and the sludge retention time increased to >200 days compared to 2200 mg/l and 8-10 days, respectively, in the system without BSP (control). Formaldehyde in the waste-water was found to be responsible for the observed toxicity. The BSP system was found to resist formaldehyde toxicity of up to 375 mg/l as against 125 mg/l in the control system. Moreover, the BSP system recovered from the toxicity much faster (15 days) than the control (25-30 days). The advantages of the BSP system in anaerobic treatment of DMT waste-water are discussed. (orig.)

  17. Biocompatible, biodegradable polymer-based, lighter than or light as water scaffolds for tissue engineering and methods for preparation and use thereof

    Science.gov (United States)

    Laurencin, Cato T. (Inventor); Pollack, Solomon R. (Inventor); Levine, Elliot (Inventor); Botchwey, Edward (Inventor); Lu, Helen H. (Inventor); Khan, Mohammed Yusuf (Inventor)

    2012-01-01

    Scaffolds for tissue engineering prepared from biocompatible, biodegradable polymer-based, lighter than or light as water microcarriers and designed for cell culturing in vitro in a rotating bioreactor are provided. Methods for preparation and use of these scaffolds as tissue engineering devices are also provided.

  18. Challenges and opportunities in using Life Cycle Assessment and Cradle to Cradle® for biodegradable bio-based polymers: a review

    DEFF Research Database (Denmark)

    Niero, Monia; Manat, Renil; Møller, Birger Lindberg

    2015-01-01

    Both Life Cycle Assessment (LCA) and Cradle to Cradle® (C2C) approaches can provide operative insightsin the design of biodegradable bio-based polymers. Some of the challenges shared by both LCA and C2Cthat need further investigation are the use of lab scale data versus primary data from establis...

  19. Performance and environmental impact of biodegradable polymers as agricultural mulching films.

    Science.gov (United States)

    Touchaleaume, François; Martin-Closas, Lluís; Angellier-Coussy, Hélène; Chevillard, Anne; Cesar, Guy; Gontard, Nathalie; Gastaldi, Emmanuelle

    2016-02-01

    In the aim of resolving environmental key issues such as irreversible soil pollution by non-biodegradable and non-recoverable polyethylene (PE) fragments, a full-scale field experiment was set up to evaluate the suitability of four biodegradable materials based on poly(butylene adipate-co-terephtalate) (PBAT) to be used as sustainable alternatives to PE for mulching application in vineyard. Initial ultimate tensile properties, functional properties during field ageing (water vapour permeability and radiometric properties), biodegradability and agronomical performance of the mulched vines (wood production and fruiting yield) were studied. In spite of their early loss of physical integrity that occurred only five months after vine planting, the four materials satisfied all the requested functional properties and led to agronomic performance as high as polyethylene. In the light of the obtained results, the mulching material lifespan was questioned in the case of long-term perennial crop such as grapevine. Taking into account their mulching efficiency and biodegradability, the four PBAT-based studied materials are proven to constitute suitable alternatives to the excessively resistant PE material. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Sustained clinical safety and efficacy of a biodegradable-polymer coated sirolimus-eluting stent in "real-world" practice: three-year outcomes of the CREATE (Multi-Center Registry of EXCEL Biodegradable Polymer Drug Eluting Stents) study.

    Science.gov (United States)

    Han, Yaling; Jing, Quanmin; Li, Yi; Yang, Lixia; Liu, Huiliang; Shang, Xiaoming; Jiang, Tiemin; Li, Zhanquan; Zhang, Hua; Yan, Gaoliang

    2012-02-01

    The CREATE is a post-marketing surveillance multicenter registry that demonstrated satisfactory angiographic and clinical (at 18 months) outcomes of a biodegradable polymer based sirolimus-eluting stent (EXCEL, JW Medical System, Weihai, China) for the treatment of patients in routine clinical practice. To evaluate the three-year clinical safety and efficacy outcomes in patients enrolled in the CREATE study. A total of 2077 all comers have been enrolled in the CREATE study at 59 centers from four countries. Recommended antiplatelet regimen was clopidogrel and aspirin for six months followed by chronic aspirin therapy. The prespecified primary outcome was the rate of major adverse cardiac events (MACE) at 12, 18, and 36 months. Clinical follow-up was completed in 2025 (97.5%) patients at three years. The average duration of clopidogrel treatment was 199.8 ± 52.7 days and 80.5% of discharged patients discontinued clopidogrel at six months. The cumulative rate of MACE was 4.5% and the rate of stent thrombosis was 1.53% at three years. At six months to three years, prolonged clopidogrel therapy (>6 months) was not beneficial in reducing cumulative hazards of MACE (3.4% vs. 3.1%, log rank P = 0.725) or stent thrombosis (1.5% vs. 0.6%, log rank P = 0.053). This study demonstrates sustained three-year clinical safety and efficacy of biodegradable polymer-based sirolimus-eluting stents when used with six months of dual antiplatelet therapy in a "real-world" setting. Copyright © 2011 Wiley Periodicals, Inc.

  1. Bioactivity of freeze-dried platelet-rich plasma in an adsorbed form on a biodegradable polymer material.

    Science.gov (United States)

    Nakajima, Yu; Kawase, Tomoyuki; Kobayashi, Mito; Okuda, Kazuhiro; Wolff, Larry F; Yoshie, Hiromasa

    2012-01-01

    Owing to the necessity for the immediate preparation from patients' blood, autologous platelet-rich plasma (PRP) limits its clinical applicability. To address this concern and respond to emergency care and other unpredictable uses, we have developed a freeze-dried PRP in an adsorbed form on a biodegradable polymer material (Polyglactin 910). On the polymer filaments of PRP mesh, which was prepared by coating the polymer mesh with human fresh PRP and subsequent freeze-drying, platelets were incorporated, and related growth factors were preserved at high levels. This new PRP mesh preparation significantly and reproducibly stimulated the proliferation of human periodontal ligament cells in vitro and neovascularization in a chorioallantoic membrane assay. A full-thickness skin defect model in a diabetic mouse demonstrated the PRP mesh, although prepared from human blood, substantially facilitated angiogenesis, granulation tissue formation, and re-epithelialization without inducing severe inflammation in vivo. These data demonstrate that our new PRP mesh preparation functions as a bioactive material to facilitate tissue repair/regeneration. Therefore, we suggest that this bioactive material, composed of allogeneic PRP, could be clinically used as a promising alternative in emergency care or at times when autologous PRP is not prepared immediately before application.

  2. Biodegradation study of enzymatically catalyzed interpenetrating polymer network: Evaluation of agrochemical release and impact on soil fertility

    Directory of Open Access Journals (Sweden)

    Saruchi

    2016-03-01

    Full Text Available A novel interpenetrating polymer network (IPN has been synthesized through enzymatic initiation using lipase as initiator, glutaraldehyde as cross-linker, acrylic acid as primary monomer and acrylamide as secondary monomer. Biodegradability of synthesized interpenetrating polymer network was studied through soil burial and composting methods. Synthesized hydrogel was completely degraded within 70 days using composting method, while it was 86.03% degraded within 77 days using soil burial method. This was confirmed by Fourier transform Infrared spectroscopy (FTIR and Scanning electron microscopy (SEM techniques. Synthesized interpenetrating polymer network hydrogel was used as a device for controlled release of urea and also act as water releasing device. Their impact on soil fertility and plant growth was also studied. The initial diffusion coefficient has a greater value than the later diffusion coefficient indicating a higher fertilizer release rate during the early stage. Fertilizer release kinetic was also studied which showed Non-Fickian diffusion behavior, as the rate of fertilizer release was comparable to the relaxation time of the synthesized matrix. Synthesized IPN enhance the water uptake capacity up to 6.2% and 7.2% in sandy loam and clay soil, respectively.

  3. Nanoporous materials modified with biodegradable polymers as models for drug delivery applications

    DEFF Research Database (Denmark)

    Gruber, Mathias F; Schulte, Lars; Ndoni, Sokol

    2013-01-01

    Polymers play a central role in the development of carriers for diagnostic and therapeutic agents. Especially the use of either degradable polymers or porous materials to encapsulate drug compounds in order to obtain steady drug release profiles has received much attention. We present here a proof...... of principle for a system combining these two encapsulation methods and consisting of a nanoporous polymer (NP) with the pores filled with a degradable polymer mixed with a drug model. Rhodamine 6G (R6G) mixed with Poly(l-Lactic Acid) (PLLA) were confined within the 14nm pores of a NP with gyroid morphology...

  4. Effect of chemical heterogeneity of biodegradable polymers on surface energy: A static contact angle analysis of polyester model films.

    Science.gov (United States)

    Belibel, R; Avramoglou, T; Garcia, A; Barbaud, C; Mora, L

    2016-02-01

    Biodegradable and bioassimilable poly((R,S)-3,3 dimethylmalic acid) (PDMMLA) derivatives were synthesized and characterized in order to develop a new coating for coronary endoprosthesis enabling the reduction of restenosis. The PDMMLA was chemically modified to form different custom groups in its side chain. Three side groups were chosen: the hexyl group for its hydrophobic nature, the carboxylic acid and alcohol groups for their acid and neutral hydrophilic character, respectively. The sessile drop method was applied to characterize the wettability of biodegradable polymer film coatings. Surface energy and components were calculated. The van Oss approach helped reach not only the dispersive and polar acid-base components of surface energy but also acid and basic components. Surface topography was quantified by atomic force microscopy (AFM) and subnanometer average values of roughness (Ra) were obtained for all the analyzed surfaces. Thus, roughness was considered to have a negligible effect on wettability measurements. In contrast, heterogeneous surfaces had to be corrected by the Cassie-Baxter equation for copolymers (10/90, 20/80 and 30/70). The impact of this correction was quantified for all the wettability parameters. Very high relative corrections (%) were found, reaching 100% for energies and 30% for contact angles. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Particles on the move: intracellular trafficking and asymmetric mitotic partitioning of nanoporous polymer particles.

    Science.gov (United States)

    Yan, Yan; Lai, Zon W; Goode, Robert J A; Cui, Jiwei; Bacic, Tess; Kamphuis, Marloes M J; Nice, Edouard C; Caruso, Frank

    2013-06-25

    Nanoporous polymer particles (NPPs) prepared by mesoporous silica templating show promise as a new class of versatile drug/gene delivery vehicles owning to their high payload capacity, functionality, and responsiveness. Understanding the cellular dynamics of such particles, including uptake, intracellular trafficking, and distribution, is an important requirement for their development as therapeutic carriers. Herein, we examine the spatiotemporal map of the cellular processing of submicrometer-sized disulfide-bonded poly(methacrylic acid) (PMASH) NPPs in HeLa cells using both flow cytometry and fluorescence microscopy. The data show that the PMASH NPPs are transported from the early endosomes to the lysosomes within a few minutes. Upon cell division, the lysosome-enclosed PMASH NPPs are distributed asymmetrically between two daughter cells. Statistical analysis of cells during cytokinesis suggests that partitioning of particles is biased with an average segregation deviation of 60%. Further, two-dimensional difference gel electrophoresis (2D-DIGE) analysis reveals that 127 out of 3059 identified spots are differentially regulated upon exposure to the PMASH NPPs. Pathway analysis of the proteomics data suggests that ubiquitylation, a reversible modification of cellular proteins with ubiquitin, plays a central role in overall cellular responses to the particles. These results provide important insights into the cellular dynamics and heterogeneity of NPPs, as well as the mechanisms that regulate the motility of these particles within cells, all of which have important implications for drug susceptibility characteristics in cancer cells using particle-based carriers.

  6. Late clinical outcomes after implantation of drug-eluting stents coated with biodegradable polymers: 3-year follow-up of the PAINT randomised trial.

    Science.gov (United States)

    Lemos, Pedro A; Moulin, Bruno; Perin, Marco A; Oliveira, Ludmilla A R R; Arruda, J Airton; Lima, Valter C; Lima, Antonio A G; Caramori, Paulo R A; Medeiros, Cesar R; Barbosa, Mauricio R; Brito, Fabio S; Ribeiro, Expedito E

    2012-05-15

    The long-term clinical performance of drug-eluting stents (DES) coated with biodegradable polymers is poorly known. A total of 274 coronary patients were randomly allocated to paclitaxel-eluting stents, sirolimus-eluting stents, or bare metal stents (2:2:1 ratio). The two DES used the same biodegradable polymers and were identical except for the drug. At three years, the pooled DES population had similar rates of cardiac death or myocardial infarction (9.0% vs. 7.1; p=0.6), but lower risk of repeat interventions (10.0% vs. 29.9%; pbiodegradable-polymer coated DES releasing either paclitaxel or sirolimus were effective in reducing the 3-year rate of re-interventions.

  7. Synthesis and characterization of polymers based on citric acid and glycerol: Its application in non-biodegradable polymers

    Directory of Open Access Journals (Sweden)

    Jaime Alfredo Mariano-Torres

    2015-01-01

    Full Text Available El notable incremento mundial en el consumo de plásticos y su l argo tiempo de residencia en el ambiente muestran la gran neces idad de productos con caracterís ticas biodegradables. En este proyecto fueron desarrollados polímeros biodegradables a base del ácido cítrico y del glicerol. La síntesis de esto s se lleva a cabo a diferentes condiciones de concentración y a temperatura constante. Se des arrollaron mediante un proceso económicamente viable. Se caracterizaron p or medio de las siguientes técnicas: Numero ácido, espectroscop ia infrarroja FTIR, índice de refracc ión, viscosidad, análisis de impacto, ensayo de tensión, dure za, calorimetría, el % de Humed ad (método de la estufa con recirculación de aire, determinación de densi dad, además de pruebas cualitativas para corroborar su biodegra dabilidad. Los polímeros elaborados fueron mezclados con una formulación de PVC grado médico, obteniendo un polímero hibrido y se pudo observar que modifica sus propiedades mecánicas.

  8. Biodegradable and bio-based polymers: future prospects of eco-friendly plastics.

    Science.gov (United States)

    Iwata, Tadahisa

    2015-03-09

    Currently used plastics are mostly produced from petrochemical products, but there is a growing demand for eco-friendly plastics. The use of bio-based plastics, which are produced from renewable resources, and biodegradable plastics, which are degraded in the environment, will lead to a more sustainable society and help us solve global environmental and waste management problems. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Effect of particle morphology on the mechanical and thermo-mechanical behavior of polymer composites

    OpenAIRE

    Oréfice, R. L.; Hench, L. L.; Brennan, A. B.

    2001-01-01

    Fiber reinforced polymer composites have been used in many applications, such as in automobile, aerospace and naval industries, due basically to their high strength-to-weight and modulus-to-weight, among other properties. Even though particles are usually not able to lead to the level of reinforcement of fibers, particle reinforced polymer composites have been proposed for many new applications due to their low cost, easy fabrication and isotropic properties. In this work, polymer composites ...

  10. Biodegradability and mechanical properties of PP/HMSPP and natural polymers bio-composites in function of gamma-irradiation

    International Nuclear Information System (INIS)

    Cardoso, Elisabeth C.L.; Scagliusi, Sandra R.; Lima, Luis F.C.P.; Bueno, Nelson R.; Parra, Duclerc F.; Lugao, Ademar B.

    2013-01-01

    PP, expressed as C n H 2n , is one of the most widely used linear hydrocarbon polymers; its versatility arises from the fact that it is made from cheap petrochemical feed stocks through efficient catalytic polymerization process and easy processing to various products. Thus, enormous production and utilization of polymers, in general, lead to their accumulation in the environment, since they are not easily degraded by microorganisms, presenting a serious source of pollution affecting both flora and fauna. These polymers are very bio-resistant due to the involvement of only carbon atoms in main chain with no hydrolyzable functional group. Non-degradable plastics accumulate in the environment at a rate of 25 million tons per year. In recent years, as a result of growing environmental awareness, natural polymers have been increasingly used as reinforcing fillers in thermoplastic composite materials. Sugarcane bagasse was used as reinforcing filler, considering that Brazil is the largest world producer of this crop, with a 101 Mt main agro-industrial residue of sugarcane processing from 340 Mt of sugarcane. Bio-composites were compounded on a twin-screw extruder and samples collected directly from the die. This study aims to investigate mechanical properties of PP/HMSPP-sugarcane bagasse 10, 15, 30 and 50% blends gamma-irradiated at 50, 100, 150 and 200 kGy doses. Degradation essays will comprise DSC and TGA tests and biodegradability behavior will be indicated by Laboratory Soil Burial Test. The main objective of this work is to support the application of these composites as environmentally friendly materials, without prejudicing mechanicals properties, in spite of applied gamma-irradiation. (author)

  11. Biodegradability and mechanical properties of PP/HMSPP and natural polymers bio-composites in function of gamma-irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Cardoso, Elisabeth C.L.; Scagliusi, Sandra R.; Lima, Luis F.C.P.; Bueno, Nelson R.; Parra, Duclerc F.; Lugao, Ademar B., E-mail: eclcardo@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    PP, expressed as C{sub n}H{sub 2n}, is one of the most widely used linear hydrocarbon polymers; its versatility arises from the fact that it is made from cheap petrochemical feed stocks through efficient catalytic polymerization process and easy processing to various products. Thus, enormous production and utilization of polymers, in general, lead to their accumulation in the environment, since they are not easily degraded by microorganisms, presenting a serious source of pollution affecting both flora and fauna. These polymers are very bio-resistant due to the involvement of only carbon atoms in main chain with no hydrolyzable functional group. Non-degradable plastics accumulate in the environment at a rate of 25 million tons per year. In recent years, as a result of growing environmental awareness, natural polymers have been increasingly used as reinforcing fillers in thermoplastic composite materials. Sugarcane bagasse was used as reinforcing filler, considering that Brazil is the largest world producer of this crop, with a 101 Mt main agro-industrial residue of sugarcane processing from 340 Mt of sugarcane. Bio-composites were compounded on a twin-screw extruder and samples collected directly from the die. This study aims to investigate mechanical properties of PP/HMSPP-sugarcane bagasse 10, 15, 30 and 50% blends gamma-irradiated at 50, 100, 150 and 200 kGy doses. Degradation essays will comprise DSC and TGA tests and biodegradability behavior will be indicated by Laboratory Soil Burial Test. The main objective of this work is to support the application of these composites as environmentally friendly materials, without prejudicing mechanicals properties, in spite of applied gamma-irradiation. (author)

  12. Damage-induced hydrolyses modelling of biodegradable polymers for tendons and ligaments repair.

    Science.gov (United States)

    Vieira, André C; Guedes, Rui M; Tita, Volnei

    2015-09-18

    The use of biodegradable synthetic grafts to repair injured ligaments may overcome the disadvantages of other solutions. Apart from biological compatibility, these devices shall also be functionally compatible and temporarily displayed, during the healing process, adequate mechanical support. Laxity of these devices is an important concern. This can cause failure since it may result in joint instability. Laxity results from a progressive accumulation of plastic strain during the cyclic loading. The functional compatibility of a biodegradable synthetic graft and, therefore, the global mechanical properties of the scaffold during degradation, can be optimised using computer-aiding and numerical tools. Therefore, in this work, the ability of numerical tools to predict the mechanical behaviour of the device during its degradation is discussed. Computational approaches based on elastoplastic and viscoplastic constitutive models are also presented. These models enable to simulate the plastic strain accumulation. These computational approaches, where the material model parameters depend on the hydrolytic degradation damage, are calibrated using experimental data measured from biodegradable suture fibres at different degradation steps. Due to durability requirements the selected materials are polydioxone (PDO) and polylactic acid and poly-caprolactone blend (PLA-PCL). Computational approaches investigated are able to predict well the experimental results for both materials, in full strain range until rupture and for different degradation steps. These approaches can be further used in more complex fibrous structures, to predict its global mechanical behaviour during degradation process. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Comparison of 3 biodegradable polymer and durable polymer-based drug-eluting stents in all-comers (BIO-RESORT): Rationale and study design of the randomized TWENTE III multicenter trial

    NARCIS (Netherlands)

    Lam, Ming Kai; Sen, Hanim; Sen, Hanim; Tandjung, K.; Tandjung, K.; van Houwelingen, K. Gert; de Vries, Arie G.; Danse, Peter W.; Schotborgh, Carl E.; Scholte, Martijn; Löwik, Marije M.; Linssen, Gerard C.M.; IJzerman, Maarten Joost; van der Palen, Jacobus Adrianus Maria; Doggen, Catharina Jacoba Maria; von Birgelen, Clemens

    2014-01-01

    Aim To evaluate the safety and efficacy of 2 novel drug-eluting stents (DES) with biodegradable polymer-based coatings versus a durable coating DES. Methods and Results BIO-RESORT is an investigator-initiated, prospective, patient-blinded, randomized multicenter trial in 3540 Dutch all-comers with

  14. Nanoporous materials modified with biodegradable polymers as models for drug delivery applications

    DEFF Research Database (Denmark)

    Gruber, Mathias F; Schulte, Lars; Ndoni, Sokol

    2013-01-01

    Polymers play a central role in the development of carriers for diagnostic and therapeutic agents. Especially the use of either degradable polymers or porous materials to encapsulate drug compounds in order to obtain steady drug release profiles has received much attention. We present here a proof...... of principle for a system combining these two encapsulation methods and consisting of a nanoporous polymer (NP) with the pores filled with a degradable polymer mixed with a drug model. Rhodamine 6G (R6G) mixed with Poly(l-Lactic Acid) (PLLA) were confined within the 14nm pores of a NP with gyroid morphology...... the hydrolysis of PLLA. The obtained release profiles demonstrate that the degradation of PLLA in nanoporous confinement is significantly slower than the degradation of unconfined PLLA. The release of R6G encapsulated in PLLA becomes correspondingly slower, while the initial burst release virtually disappears...

  15. A randomised comparison of a novel abluminal groove-filled biodegradable polymer sirolimus-eluting stent with a durable polymer everolimus-eluting stent: clinical and angiographic follow-up of the TARGET I trial.

    Science.gov (United States)

    Gao, Run-Lin; Xu, Bo; Lansky, Alexandra J; Yang, Yue-Jin; Ma, Chang-Sheng; Han, Ya-Ling; Chen, Shao-Liang; Li, Hui; Zhang, Rui-Yan; Fu, Guo-Sheng; Yuan, Zu-Yi; Jiang, Hong; Huo, Yong; Li, Wei; Zhang, Yao-Jun; Leon, Martin B

    2013-05-20

    The study sought to evaluate the safety and efficacy of FIREHAWK, a novel abluminal groove-filled biodegradable polymer sirolimus-eluting stent (SES) for treating patients with single de novo coronary lesions compared with the durable polymer everolimus-eluting stent (EES) XIENCE V. A total of 458 patients with single de novo native coronary lesions ≤24 mm in length and a coronary artery ≥2.25 to ≤4.0 mm in diameter were enrolled in the TARGET I study, a prospective, randomised, non-inferiority trial. The primary endpoint was in-stent late lumen loss (LLL) at nine-month follow-up. The secondary endpoint, target lesion failure (TLF), was defined as the composite of cardiac death, target vessel myocardial infarction (TVMI), or ischaemia-driven target lesion revascularisation (iTLR). Patients were centrally randomised to treatment with either biodegradable polymer SES (n=227) or durable polymer EES (n=231). The nine-month in-stent LLL of the biodegradable polymer SES was comparable to the EES group (0.13 ± 0.24 mm vs. 0.13 ± 0.18 mm, p=0.94; difference and 95% confidence interval 0.00 [-0.04, 0.04] mm; p for non-inferiority 0.05). No definite/probable stent thrombosis was observed in both of these groups. In the multicentre TARGET I trial, the novel abluminal groove-filled biodegradable polymer SES FIREHAWK was non-inferior to the durable polymer EES XIENCE V with respect to the primary endpoint of in-stent LLL at nine months for treating patients with single de novo coronary lesions. The incidences of clinical endpoints were low in both of the stents at 12-month follow-up. (ClinicalTrials.gov identifier: NCT01196819).

  16. Molecular Design and Evaluation of Biodegradable Polymers Using a Statistical Approach

    Science.gov (United States)

    Lewitus, Dan; Rios, Fabian; Rojas, Ramiro; Kohn, Joachim

    2013-01-01

    The challenging paradigm of bioresorbable polymers, whether in drug delivery or tissue engineering, states that a fine-tuning of the interplay between polymer properties (e.g., thermal, degradation), and the degree of cell/tissue replacement and remodeling is required. In this paper we describe how changes in the molecular architecture of a series of terpolymers allow for the design of polymers with varying glass transition temperatures and degradation rates. The effect of each component in the terpolymers is quantified via design of experiment (DoE) analysis. A linear relationship between terpolymer components and resulting Tg (ranging from 34 to 86 °C) was demonstrated. These findings were further supported with mass-per-flexible-bond (MPFB) analysis. The effect of terpolymer composition on the in vitro degradation of these polymers revealed molecular weight loss ranging from 20 to 60% within the first 24 hours. DoE modeling further illustrated the linear (but reciprocal) relationship between structure elements and degradation for these polymers. Thus, we describe a simple technique to provide insight into the structure property relationship of degradable polymers, specifically applied using a new family of tyrosine-derived polycarbonates, allowing for optimal design of materials for specific applications. PMID:23888354

  17. Molecular design and evaluation of biodegradable polymers using a statistical approach.

    Science.gov (United States)

    Lewitus, Dan Y; Rios, Fabian; Rojas, Ramiro; Kohn, Joachim

    2013-11-01

    The challenging paradigm of bioresorbable polymers, whether in drug delivery or tissue engineering, states that a fine-tuning of the interplay between polymer properties (e.g., thermal, degradation), and the degree of cell/tissue replacement and remodeling is required. In this paper we describe how changes in the molecular architecture of a series of terpolymers allow for the design of polymers with varying glass transition temperatures and degradation rates. The effect of each component in the terpolymers is quantified via design of experiment (DoE) analysis. A linear relationship between terpolymer components and resulting Tg (ranging from 34 to 86 °C) was demonstrated. These findings were further supported with mass-per-flexible-bond analysis. The effect of terpolymer composition on the in vitro degradation of these polymers revealed molecular weight loss ranging from 20 to 60 % within the first 24 h. DoE modeling further illustrated the linear (but reciprocal) relationship between structure elements and degradation for these polymers. Thus, we describe a simple technique to provide insight into the structure property relationship of degradable polymers, specifically applied using a new family of tyrosine-derived polycarbonates, allowing for optimal design of materials for specific applications.

  18. Photoluminescent and biodegradable polycitrate-polyethylene glycol-polyethyleneimine polymers as highly biocompatible and efficient vectors for bioimaging-guided siRNA and miRNA delivery.

    Science.gov (United States)

    Wang, Min; Guo, Yi; Yu, Meng; Ma, Peter X; Mao, Cong; Lei, Bo

    2017-05-01

    Development of biodegradable and biocompatible non-viral vectors with intrinsical multifunctional properties such as bioimaging ability for highly efficient nucleic acids delivery still remains a challenge. Here, a biodegradable poly (1,8-octanedio-citric acid)-co-polyethylene glycol grafted with polyethyleneimine (PEI) (POCG-PEI) polymers with the photoluminescent capacity were synthesized for nucleic acids delivery (siRNA and miRNA). POCG-PEI polymers can efficiently bind various nucleic acids, protect them against enzymatic degradation and release the genes in the presence of polyanionic heparin. POCG-PEI also showed a significantly low cytotoxicity, enhanced cellular uptake and high transfection efficiency of nucleic acids, as compared to commercial transfection agents, lipofectamine 2000 (Lipo) and polyethylenimine (PEI 25K). POCG-PEI polymers demonstrate an excellent photostability, which allows for imaging the cells and real-time tracking the nucleic acids delivery. The photoluminescent property, low cytotoxicity, biodegradation, good gene binding and protection ability and high genes delivery efficiency make POCG-PEI highly competitive as a non-virus vector for genes delivery and real-time bioimaging applications. Our results may be also an important step for designing biodegradable biomaterials with multifunctional properties towards bioimaging-guided genes therapeutic applications. Here, a biodegradable poly (1,8-octanedio-citric acid)-co-polyethylene glycol grafted with polyethyleneimine (PEI) (POCG-PEI) polymers with controlled photoluminescent capacity were synthesized for nucleic acids delivery (siRNA and miRNA). POCG-PEI polymers can efficiently bind various nucleic acids, protect them against enzymatic degradation and release the genes in the presence of polyanionic heparin. POCG-PEI also showed a significantly low cytotoxicity, enhanced cellular uptake and high transfection efficiency of nucleic acids, as compared to commercial transfection agents

  19. Novel meloxicam releasing electrospun polymer/ceramic reinforced biodegradable membranes for periodontal regeneration applications

    International Nuclear Information System (INIS)

    Yar, Muhammad; Farooq, Ariba; Shahzadi, Lubna; Khan, Abdul Samad; Mahmood, Nasir; Rauf, Abdul; Chaudhry, Aqif Anwar; Rehman, Ihtesham ur

    2016-01-01

    Periodontal disease is associated with the destruction of periodontal tissues, along with other disorders/problems including inflammation of tissues and severe pain. This paper reports the synthesis of meloxicam (MX) immobilized biodegradable chitosan (CS)/poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) based electrospun (e-spun) fibers and films. Electrospinning was employed to produce drug loaded fibrous mats, whereas films were generated by solvent casting method. In-vitro drug release from materials containing varying concentrations of MX revealed that the scaffolds containing higher amount of drug showed comparatively faster release. During initial first few hours fast release was noted from membranes and films; however after around 5 h sustained release was achieved. The hydrogels showed good swelling property, which is highly desired for soft tissue engineered implants. To investigate the biocompatibility of our synthesized materials, VERO cells (epithelial cells) were selected and cell culture results showed that these all materials were non-cytotoxic and also these cells were very well proliferated on these synthesized scaffolds. These properties along with the anti-inflammatory potential of our fabricated materials suggest their effective utilization in periodontital treatments. - Highlights: • NSAIDs releasing scaffolds for periodontal regeneration applications • Meloxicam immobilized biodegradable nanocomposite electrospun membranes and films • Good swelling properties • Controlled drug release • VERO cells were very well proliferated and synthesized materials were found to be non-cytotoxic.

  20. Novel meloxicam releasing electrospun polymer/ceramic reinforced biodegradable membranes for periodontal regeneration applications

    Energy Technology Data Exchange (ETDEWEB)

    Yar, Muhammad, E-mail: drmyar@ciitlahore.edu.pk [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Farooq, Ariba [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Shahzadi, Lubna; Khan, Abdul Samad [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Mahmood, Nasir [Department of Allied Health Sciences and Chemical Pathology, Department of Human Genetics and Molecular Biology, University of Health Sciences, Lahore (Pakistan); Rauf, Abdul [Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100 (Pakistan); Chaudhry, Aqif Anwar [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Rehman, Ihtesham ur [Interdisciplinary Research Center in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Department of Materials Science and Engineering, The Kroto Research Institute, The University of Sheffield, North Campus, Broad Lane, Sheffield S3 7HQ (United Kingdom)

    2016-07-01

    Periodontal disease is associated with the destruction of periodontal tissues, along with other disorders/problems including inflammation of tissues and severe pain. This paper reports the synthesis of meloxicam (MX) immobilized biodegradable chitosan (CS)/poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) based electrospun (e-spun) fibers and films. Electrospinning was employed to produce drug loaded fibrous mats, whereas films were generated by solvent casting method. In-vitro drug release from materials containing varying concentrations of MX revealed that the scaffolds containing higher amount of drug showed comparatively faster release. During initial first few hours fast release was noted from membranes and films; however after around 5 h sustained release was achieved. The hydrogels showed good swelling property, which is highly desired for soft tissue engineered implants. To investigate the biocompatibility of our synthesized materials, VERO cells (epithelial cells) were selected and cell culture results showed that these all materials were non-cytotoxic and also these cells were very well proliferated on these synthesized scaffolds. These properties along with the anti-inflammatory potential of our fabricated materials suggest their effective utilization in periodontital treatments. - Highlights: • NSAIDs releasing scaffolds for periodontal regeneration applications • Meloxicam immobilized biodegradable nanocomposite electrospun membranes and films • Good swelling properties • Controlled drug release • VERO cells were very well proliferated and synthesized materials were found to be non-cytotoxic.

  1. Effects of Temperature on Dynamic Properties of a Biodegradable Polymer Made from Corn Starch

    Science.gov (United States)

    Nishida, Masahiro; Ito, Noriomi; Kawase, Hiroyuki; Tanaka, Koichi

    The effect of strain rate on compressive properties of starch-based biodegradable plastics (Nihon Cornstarch Co., CPR-M2) was examined. Dynamic stress-strain curves of starch-based biodegradable plastics were measured over a wide range of strain rates from 10-5 s-1 to 104 s-1, using a quasi-static compression testing machine and a split Hopkinson pressure bar (SHPB) system. The strain rate slightly affected Young's modulus and considerably increased 7% flow stress. Empirical equation for 7% flow stress was derived for the strain rates from 10-5 s-1 to 104 s-1. In addition, the effect of temperature on Young's modulus and flow stress was also examined in a range from 4°C to 63°C. A master curve of 7% flow stress, reduced to 24°C, was made. The values of activation energies related to the α and β relaxation processes were respectively estimated from the master curve of 7% flow stress and from the best fit of equations based on Ree-Eyring theory and Bauwens' treatment. Temperature measurement of specimens was also made using thermocouples during dynamic compression.

  2. Junctions between metals and blends of conducting and biodegradable polymers (PLLA-PPy and PCL-PPy).

    Science.gov (United States)

    Boutry, C M; Müller, M; Hierold, C

    2012-08-01

    The junctions between newly developed biodegradable conducting polymers (polylactide-polypyrrole PLLA-PPy and polycaprolactone-polypyrrole PCL-PPy) and metal electrodes (Au, Au/Cu, Ag, Ag/Cu, Cu, Cr/Au/Cu, Pd/Au/Cu, Pt/Au/Cu) were studied. The objective was to determine the composite/metal combination having the lowest possible contact resistance and ohmic characteristics. In a first step, different surface treatments, adhesion and metal layers were tested in order to evaluate the contact resistance. Then the current-voltage (IV) characteristics were measured and both ohmic and rectifying behaviour were observed depending on the polymer/metal junctions investigated. The surface treatments studied included an argon sputtering step and a grinding of the polymer surface with the objective of improving the contact between the metal electrode and the polymer. It was found that the most favourable conditions resulted from a process flow without argon sputtering, without grinding for PLLA-PPy and with a slight grinding for PCL-PPy. Moreover the most favourable metal electrodes for PLLA-PPy were Pd/Au/Cu, while the best compromise for PCL-PPy was to use Au/Cu. For the rectifying polymer/metal junctions, the standard thermionic emission model modified with a series resistance was successfully applied to the measured current-voltage IV characteristics. The saturation current density J0, series resistance R, ideality diode factor n and barrier height φB were investigated. The Chot functions were computed for each rectifying junction and the corresponding threshold voltages were calculated. Finally the conductivity of both composites was evaluated as a function of temperature in the range of 30 °C to 80 °C. For PLLA-PPy a decrease of the resistivity was observed when the temperature was increasing, while no clearly recognisable pattern was identified for PCL-PPy in this temperature range. The electrical conductivity of the PLLA-PPy samples was found to follow the empirical

  3. A Biodegradable Thermoset Polymer Made by Esterification of Citric Acid and Glycerol

    Science.gov (United States)

    Halpern, Jeffrey M.; Urbanski, Richard; Weinstock, Allison K.; Iwig, David F.; Mathers, Robert T.; von Recum, Horst

    2014-01-01

    A new biomaterial, a degradable thermoset polymer, was made from simple, economical, biocompatable monomers without the need for a catalyst. Glycerol and citric acid, non-toxic and renewable reagents, were crosslinked by a melt polymerization reaction at temperatures from 90-150°C. Consistent with a condensation reaction, water was determined to be the primary byproduct. The amount of crosslinking was controlled by the reaction conditions, including temperature, reaction time, and ratio between glycerol and citric acid. Also, the amount of crosslinking was inversely proportional to the rate of degradation. As a proof-of-principle for drug delivery applications, gentamicin, an antibiotic, was incorporated into the polymer with preliminary evaluations of antimicrobial activity. The polymers incorporating gentamicin had significantly better bacteria clearing of Staphylococcus aureus compared to non-gentamicin gels for up to nine days. PMID:23737239

  4. Quantitative structure-activity relationships for green algae growth inhibition by polymer particles.

    Science.gov (United States)

    Nolte, Tom M; Peijnenburg, Willie J G M; Hendriks, A Jan; van de Meent, Dik

    2017-07-01

    After use and disposal of chemical products, many types of polymer particles end up in the aquatic environment with potential toxic effects to primary producers like green algae. In this study, we have developed Quantitative Structure-Activity Relationships (QSARs) for a set of highly structural diverse polymers which are capable to estimate green algae growth inhibition (EC50). The model (N = 43, R 2  = 0.73, RMSE = 0.28) is a regression-based decision tree using one structural descriptor for each of three polymer classes separated based on charge. The QSAR is applicable to linear homo polymers as well as copolymers and does not require information on the size of the polymer particle or underlying core material. Highly branched polymers, non-nitrogen cationic polymers and polymeric surfactants are not included in the model and thus cannot be evaluated. The model works best for cationic and non-ionic polymers for which cellular adsorption, disruption of the cell wall and photosynthesis inhibition were the mechanisms of action. For anionic polymers, specific properties of the polymer and test characteristics need to be known for detailed assessment. The data and QSAR results for anionic polymers, when combined with molecular dynamics simulations indicated that nutrient depletion is likely the dominant mode of toxicity. Nutrient depletion in turn, is determined by the non-linear interplay between polymer charge density and backbone flexibility. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Enhancement of the optical properties of a new radiochromic dosimeter based on aliphatic-aromatic biodegradable polymers

    Energy Technology Data Exchange (ETDEWEB)

    Schimitberger, Thiago, E-mail: tschimitberger@ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Escola de Engenharia. Departamento de Engenharia Nuclear; Faria, Luiz O., E-mail: farialo@cdtn.br [Centro de desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-07-01

    The development of a dosimeter that is of low cost, easy to process without dependence on expensive complex instruments and environment friendly is a challenging in irradiation quality control. Recently, an aliphatic-aromatic biodegradable polymer has been proposed as radiochromic dosimeter. The dosimeter is based on biodegradable poly(butylene adipate-co-terephthalate) copolymers (PBAT). In order to improve the photoluminescence (PL) properties of PBAT, increasing its range of applicability (50 kGy to 1000 kGy), this work investigates the influence of solution concentration in the dose response. Films with thickness of c.a. 80 μm were produce by wirebar coating, a simple deposition method for preparing large areas of organic films at low cost. The irradiation of samples was performed at room temperature using a Co-60 source at dose rate of 20 kGy/h. The films were exposed to doses ranging from 501 kGy to 1000 kGy. A 405 nm LED light source was used to excite the films. The USB2000 spectrometer made by Ocean Optics was used to collect the emission spectra of the luminescent films. The photoluminescent intensity captured by the spectrometer present linear radiation dose dependence. The maximum PL for the film sample made from a 0.05 g.mL{sup -1} solution is 1.5 (a.u.) while it is about 3.5 (a.u.) for a film sample made from a 0.2 mg.mL{sup -1} solution, when irradiated with 1000 kGy. These results indicate that PBAT films have great potential to be used as a high gamma dose radiochromic dosimeter over a wide dose range, expanding its applicability for different radiations process. (author)

  6. Polímeros biodegradáveis - uma solução parcial para diminuir a quantidade dos resíduos plásticos Biodegradable polymers - a partial way for decreasing the amount of plastic waste

    Directory of Open Access Journals (Sweden)

    Sandra Mara Martins Franchetti

    2006-07-01

    Full Text Available The large use of plastics has generated a waste deposit problem. Today plastic wastes represent 20% in volume of the total waste in the municipal landfills. To solve the disposal problem of plastics methods have been employed such as incineration, recycling, landfill disposal, biodegradation and the use of biodegradable polymers. Incineration of plastic wastes provokes pollution due to the production of poisonous gases. Recycling is important to reduce final costs of plastic materials, but is not enough in face of the amount of discarded plastic. In landfills plastic wastes remain undegraded for a long time, causing space and pollution problems. Biodegradation is a feasible method to treat some plastics, but intensive research is necessary to find conditions for the action of microorganisms. All of these methods are important and the practical application of each one depends on the type and amount of the plastic wastes and the environmental conditions. Therefore, a great deal of research has focused on developing biodegradable plastics and its application because it is an important way for minimizing the effect of the large volume of plastic waste discarded in the world.

  7. Nanoporous materials modified with biodegradable polymers as models for drug delivery applications.

    Science.gov (United States)

    Gruber, Mathias F; Schulte, Lars; Ndoni, Sokol

    2013-04-01

    Polymers play a central role in the development of carriers for diagnostic and therapeutic agents. Especially the use of either degradable polymers or porous materials to encapsulate drug compounds in order to obtain steady drug release profiles has received much attention. We present here a proof of principle for a system combining these two encapsulation methods and consisting of a nanoporous polymer (NP) with the pores filled with a degradable polymer mixed with a drug model. Rhodamine 6G (R6G) mixed with Poly(L-Lactic Acid) (PLLA) were confined within the 14 nm pores of a NP with gyroid morphology derived from a diblock copolymer precursor. Glass transition, crystallization and melting of free and confined PLLA were monitored by differential scanning calorimetry. Release profiles for R6G were measured in methanol-water solvents at pH 13, which works as an accelerated release test by speeding up the hydrolysis of PLLA. The obtained release profiles demonstrate that the degradation of PLLA in nanoporous confinement is significantly slower than the degradation of unconfined PLLA. The release of R6G encapsulated in PLLA becomes correspondingly slower, while the initial burst release virtually disappears. These findings suggest that the presented proof of principle constitutes a promising basis for the development of novel implantable drug delivery systems. Copyright © 2013 Elsevier Inc. All rights reserved.

  8. Casein and soybean protein-based thermoplastics and composites as alternative biodegradable polymers for biomedical applications

    NARCIS (Netherlands)

    Vaz, C.M.; Fossen, M.; Tuil, van R.F.; Graaf, de L.A.; Reis, R.L.; Cunha, A.M.

    2003-01-01

    This work reports on the development and characterization of novel meltable polymers and composites based on casein and soybean proteins. The effects of inert (Al2O3) and bioactive (tricalcium phosphate) ceramic reinforcements over the mechanical performance, water absorption, and bioactivity

  9. Tissue ingrowth and degradation of two biodegradable porous polymers with different porosities and pore sizes.

    NARCIS (Netherlands)

    Tienen, T. van; Heijkants, R.G.J.C.; Buma, P.; Groot, J.H. de; Pennings, A.J.; Veth, R.P.H.

    2002-01-01

    Commonly, spontaneous repair of lesions in the avascular zone of the knee meniscus does not occur. By implanting a porous polymer scaffold in a knee meniscus defect, the lesion is connected with the abundantly vascularized knee capsule and healing can be realized. Ingrowth of fibrovascular tissue

  10. Tissue ingrowth polymers and degradation of two biodegradable porous with different porosities and pore sizes

    NARCIS (Netherlands)

    van Tienen, TG; Heijkants, RGJC; Buma, P; de Groot, JH; Pennings, AJ; Veth, RPH

    Commonly, spontaneous repair of lesions in the avascular zone of the knee meniscus does not occur. By implanting a porous polymer scaffold in a knee meniscus defect, the lesion is connected with the abundantly vascularized knee capsule and heating can be realized. Ingrowth of fibrovascular tissue

  11. Impact of in situ polymer coating on particle dispersion into solid laser-generated nanocomposites.

    Science.gov (United States)

    Wagener, Philipp; Brandes, Gudrun; Schwenke, Andreas; Barcikowski, Stephan

    2011-03-21

    The crucial step in the production of solid nanocomposites is the uniform embedding of nanoparticles into the polymer matrix, since the colloidal properties or specific physical properties are very sensitive to particle dispersion within the nanocomposite. Therefore, we studied a laser-based generation method of a nanocomposite which enables us to control the agglomeration of nanoparticles and to increase the single particle dispersion within polyurethane. For this purpose, we ablated targets of silver and copper inside a polymer-doped solution of tetrahydrofuran by a picosecond laser (using a pulse energy of 125 μJ at 33.3 kHz repetition rate) and hardened the resulting colloids into solid polymers. Electron microscopy of these nanocomposites revealed that primary particle size, agglomerate size and particle dispersion strongly depend on concentration of the polyurethane added before laser ablation. 0.3 wt% polyurethane is the optimal polymer concentration to produce nanocomposites with improved particle dispersion and adequate productivity. Lower polyurethane concentration results in agglomeration whereas higher concentration reduces the production rate significantly. The following evaporation step did not change the distribution of the nanocomposite inside the polyurethane matrix. Hence, the in situ coating of nanoparticles with polyurethane during laser ablation enables simple integration into the structural analogue polymer matrix without additives. Furthermore, it was possible to injection mold these in situ-stabilized nanocomposites without affecting particle dispersion. This clarifies that sufficient in situ stabilization during laser ablation in polymer solution is able to prevent agglomeration even in a hot polymer melt.

  12. Surface-selective laser sintering of thermolabile polymer particles using water as heating sensitizer

    Energy Technology Data Exchange (ETDEWEB)

    Antonov, E N; Krotova, L I; Minaev, N V; Minaeva, S A; Mironov, A V; Popov, V K [Institute on Laser and Information Technologies of the Russian Academy of Sciencies, Troitsk, Moscow (Russian Federation); Bagratashvili, V N [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

    2015-11-30

    We report the implementation of a novel scheme for surface-selective laser sintering (SSLS) of polymer particles, based on using water as a sensitizer of laser heating and sintering of particles as well as laser radiation at a wavelength of 1.94 μm, corresponding to the strong absorption band of water. A method of sintering powders of poly(lactide-co-glycolide), a hydrophobic bioresorbable polymer, after modifying its surface with an aqueous solution of hyaluronic acid is developed. The sintering thresholds for wetted polymer are by 3 – 4 times lower than those for sintering in air. The presence of water restricts the temperature of the heated polymer, preventing its thermal destruction. Polymer matrices with a developed porous structure are obtained. The proposed SSLS method can be applied to produce bioresorbable polymer matrices for tissue engineering. (interaction of laser radiation with matter. laser plasma)

  13. Oil biodegradation

    NARCIS (Netherlands)

    Rahsepar, Shokouhalsadat; Langenhoff, Alette A.M.; Smit, Martijn P.J.; Eenennaam, van Justine S.; Murk, Tinka; Rijnaarts, Huub H.M.

    2017-01-01

    During the Deepwater Horizon (DwH) oil spill, interactions between oil, clay particles and marine snow lead to the formation of aggregates. Interactions between these components play an important, but yet not well understood, role in biodegradation of oil in the ocean water. The aim of this study

  14. A second-generation ionic liquid matrix-assisted laser desorption/ionization matrix for effective mass spectrometric analysis of biodegradable polymers.

    Science.gov (United States)

    Berthod, Alain; Crank, Jeffrey A; Rundlett, Kimber L; Armstrong, Daniel W

    2009-11-01

    A second generation ionic liquid matrix (ILM), N,N-diisopropylethylammonium alpha-cyano-4-hydroxycinnamate (DEA-CHCA), was developed for the characterization of polar biodegradable polymers. It is compared with five solid matrices typically used for the characterization of these polymers and one other new ILM. It is shown that use of the ILM, DEA-CHCA, allows maximum signal with minimum laser intensity which minimizes polymer degradation. In these conditions, the DEA-CHCA ILM is able to assist in the ionization of analytes in an efficient but soft manner. These qualities produce spectra that allow an accurate and sensitive determination of the number average molecular weights, weight average m.w., and polydispersity index of labile polar polymers. With such polymers, many solid matrices produce spectra showing extensive polymer degradation leading to the underestimation of molecular weights. The distribution of intact analyte peaks obtained with the ILM DEA-CHCA allows for identification of the fine structure of complex copolymers. ILMs were much less susceptible to effects of extraction delay times on molecular weight determination than were solid matrices. The liquid nature of the matrix is an important reason for the outstanding results obtained for labile analyte polymers. No comparable results could be obtained with any known solid matrices or other ILMs. In many cases, the manufacturers' listed molecular weights and polydispersity measurements for biodegradable polymers are determined by size-exclusion chromatography and the data obtained by that method may differ considerably from the high-precision matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) results presented here. Copyright 2009 John Wiley & Sons, Ltd.

  15. Development of modified release gliclazide biological macromolecules using natural biodegradable polymers.

    Science.gov (United States)

    Prajapati, Vipulkumar D; Mashru, Krupa H; Solanki, Himanshu K; Jani, Girish K

    2013-04-01

    Modified release biological macromolecules (beads) of gliclazide using sodium alginate combined with either gellan gum or pectin in different ratios were prepared by Ionotropic gelation method. Biological macromolecules were evaluated for different physico-chemical parameters. Increase in polymers proportion showed difficulty in production of biological macromolecules due to high viscosity of dispersion. As the polymer concentration increases, the swelling and entrapment efficiency of drug increased. Compared to all other batches and commercial modified release gliclazide tablet, formulated biological macromolecules of sodium alginate with pectin (2:1 ratio) and with gellan gum (6:0.75 ratio) exhibited spherical shape, biphasic in vitro release profile and initial high drug release followed by moderate release up to 12 h as matrix diffusion kinetics and Higuchi model as well as Korsmeyer model. Copyright © 2012 Elsevier B.V. All rights reserved.

  16. [Biodegradable synthetic polymers for the design of implantable medical devices: the ligamentoplasty case].

    Science.gov (United States)

    Garric, Xavier; Nottelet, Benjamin; Pinese, Coline; Leroy, Adrien; Coudane, Jean

    2017-01-01

    The sector of implantable medical devices is a growing sector of health products especially dynamic in the field of research. To improve the management of patients and to meet clinical requirements, researchers are developing new types of medical devices. They use different families of biomaterials presenting various chemical and physical characteristics in order for providing clinicians with health products optimized for biomedical applications. In this article, we aim to show how, starting from a family of biomaterials (degradable polymers), it is possible to design an implantable medical device for the therapeutic management of the failure of anterior cruciate ligament. The main steps leading to the design of a total ligament reinforcement are detailed. They range from the synthesis and characterization of degradable polymer to the shaping of the knitted implant, through the assessment of the study of the impact of sterilization on mechanical properties and checking cytocompatibility. © 2017 médecine/sciences – Inserm.

  17. An atomic finite element model for biodegradable polymers. Part 1. Formulation of the finite elements.

    Science.gov (United States)

    Gleadall, Andrew; Pan, Jingzhe; Ding, Lifeng; Kruft, Marc-Anton; Curcó, David

    2015-11-01

    Molecular dynamics (MD) simulations are widely used to analyse materials at the atomic scale. However, MD has high computational demands, which may inhibit its use for simulations of structures involving large numbers of atoms such as amorphous polymer structures. An atomic-scale finite element method (AFEM) is presented in this study with significantly lower computational demands than MD. Due to the reduced computational demands, AFEM is suitable for the analysis of Young's modulus of amorphous polymer structures. This is of particular interest when studying the degradation of bioresorbable polymers, which is the topic of an accompanying paper. AFEM is derived from the inter-atomic potential energy functions of an MD force field. The nonlinear MD functions were adapted to enable static linear analysis. Finite element formulations were derived to represent interatomic potential energy functions between two, three and four atoms. Validation of the AFEM was conducted through its application to atomic structures for crystalline and amorphous poly(lactide). Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Development of flash nanoprecipitation as a scalable platform for production of hybrid polymer-inorganic Janus particles

    Science.gov (United States)

    Lee, Victoria E.; Prud'Homme, Robert K.; Priestley, Rodney D.

    Polymer Janus particles, containing two or more distinct domains, can act as supports for inorganic nanoparticles, stabilizing them against aggregation and templating anisotropic functionalization of the microparticles. This anisotropy can be advantageous for applications such as biofuel upgrading, bionanosensors, and responsive materials. Here, we introduce flash nanoprecipitation (FNP) as a scalable, fast process to create hybrid polymer-inorganic Janus particles with control of particle size and anisotropy. During FNP, polymer Janus particles form by rapid intermixing of a polymer solution with a poor solvent, inducing polymer precipitation and phase separation. Inorganic nanoparticles are then adsorbed selectively onto one domain of the polymer support by exploiting electrostatic interactions between the charged particles. By tuning polymer concentration and ratio in the feed stream, the particle size and anisotropy can be controlled. We further demonstrate that these hybrid particles can simultaneously stabilize emulsions and selectively catalyze the degradation of dye in one phase. With support from the Princeton Imaging Analysis Center.

  19. Advances in Biomagnetic Interfacing Concepts Derived from Polymer-Magnetic Particle Complexes

    National Research Council Canada - National Science Library

    Riffle, Judy S

    2005-01-01

    Our research on the development and characterization of magnetic nanoparticle-polymer complexes for tile project period 6/1/03-12/31/04 has yielded approximately 10-nm diameter cobalt particles coated...

  20. A propensity score-matched comparison of biodegradable polymer vs second-generation durable polymer drug-eluting stents in a real-world population.

    Science.gov (United States)

    Zhao, Ying Jiao; Teng, Monica; Khoo, Ai Leng; Ananthakrishna, Rajiv; Yeo, Tiong Cheng; Lim, Boon Peng; Loh, Joshua P; Chan, Mark Y

    2018-04-01

    The safety and efficacy of BP-DES compared to second-generation DP-DES remain unclear in the real-world setting. We compared the clinical outcomes of biodegradable polymer drug-eluting stents (BP-DES) with second-generation durable polymer drug-eluting stents (DP-DES) in an all-comer percutaneous coronary intervention (PCI) registry. The study included a cohort of 1065 patients treated with either BP-DES or DP-DES from January 2009 through October 2015. Propensity score matching was performed to account for potential confounders and produced 497 matched pairs of patients. The primary endpoint was target lesion failure (TLF) at one-year follow-up. The rates of TLF were comparable between BP-DES and DP-DES (8.7% vs 9.1%, P = .823) at 1 year. The rates of stent thrombosis at 30 days (0.4% vs 0.4%, P = 1.00) and 1 year (0.8% vs 0.8%, P = 1.00) did not differ between BP-DES and DP-DES. There were no significant differences in other clinical outcomes including target vessel failure (8.9% vs 9.5%, P = .741), in-stent restenosis (1.8% vs 1.0%, P = .282), and cardiac death (6.4% vs 7.4%, P = .533) at 1 year. Multivariate cox regression analysis showed that the risk of TLF at one-year did not differ significantly between BP-DES and DP-DES (hazard ratio 0.94, P = .763). Efficacy and safety of BP-DES were not better than DP-DES at one-year follow-up. © 2018 John Wiley & Sons Ltd.

  1. Biodegradable polymer stents vs second generation drug eluting stents: A meta-analysis and systematic review of randomized controlled trials.

    Science.gov (United States)

    Pandya, Bhavi; Gaddam, Sainath; Raza, Muhammad; Asti, Deepak; Nalluri, Nikhil; Vazzana, Thomas; Kandov, Ruben; Lafferty, James

    2016-02-26

    To evaluate the premise, that biodegradable polymer drug eluting stents (BD-DES) could improve clinical outcomes compared to second generation permanent polymer drug eluting stents (PP-DES), we pooled the data from all the available randomized control trials (RCT) comparing the clinical performance of both these stents. A systematic literature search of PubMed, Cochrane, Google scholar databases, EMBASE, MEDLINE and SCOPUS was performed during time period of January 2001 to April 2015 for RCT and comparing safety and efficacy of BD-DES vs second generation PP-DES. The primary outcomes of interest were definite stent thrombosis, target lesion revascularization, myocardial infarction, cardiac deaths and total deaths during the study period. A total of 11 RCT's with a total of 12644 patients were included in the meta-analysis, with 6598 patients in BD-DES vs 6046 patients in second generation PP-DES. The mean follow up period was 16 mo. Pooled analysis showed non-inferiority of BD-DES, comparing events of stent thrombosis (OR = 1.42, 95%CI: 0.79-2.52, P = 0.24), target lesion revascularization (OR = 0.99, 95%CI: 0.84-1.17, P = 0.92), myocardial infarction (OR = 1.06, 95%CI: 0.86-1.29, P = 0.92), cardiac deaths (OR = 1.07, 95%CI 0.82-1.41, P = 0.94) and total deaths (OR = 0.96, 95%CI: 0.80-1.17, P = 0.71). BD-DES, when compared to second generation PP-DES, showed no significant advantage and the outcomes were comparable between both the groups.

  2. A Review on Recent Advances in Stabilizing Peptides/Proteins upon Fabrication in Hydrogels from Biodegradable Polymers

    Directory of Open Access Journals (Sweden)

    Faisal Raza

    2018-01-01

    Full Text Available Hydrogels evolved as an outstanding carrier material for local and controlled drug delivery that tend to overcome the shortcomings of old conventional dosage forms for small drugs (NSAIDS and large peptides and proteins. The aqueous swellable and crosslinked polymeric network structure of hydrogels is composed of various natural, synthetic and semisynthetic biodegradable polymers. Hydrogels have remarkable properties of functionality, reversibility, sterilizability, and biocompatibility. All these dynamic properties of hydrogels have increased the interest in their use as a carrier for peptides and proteins to be released slowly in a sustained manner. Peptide and proteins are remarkable therapeutic agents in today’s world that allow the treatment of severe, chronic and life-threatening diseases, such as diabetes, rheumatoid arthritis, hepatitis. Despite few limitations, hydrogels provide fine tuning of proteins and peptides delivery with enormous impact in clinical medicine. Novels drug delivery systems composed of smart peptides and molecules have the ability to drive self-assembly and form hydrogels at physiological pH. These hydrogels are significantly important for biological and medical fields. The primary objective of this article is to review current issues concerned with the therapeutic peptides and proteins and impact of remarkable properties of hydrogels on these therapeutic agents. Different routes for pharmaceutical peptides and proteins and superiority over other drugs candidates are presented. Recent advances based on various approaches like self-assembly of peptides and small molecules to form novel hydrogels are also discussed. The article will also review the literature concerning the classification of hydrogels on a different basis, polymers used, “release mechanisms” their physical and chemical characteristics and diverse applications.

  3. Hybrid Titanium/Biodegradable Polymer Implants with an Hierarchical Pore Structure as a Means to Control Selective Cell Movement

    Science.gov (United States)

    Vrana, Nihal Engin; Dupret, Agnès; Coraux, Christelle; Vautier, Dominique; Debry, Christian; Lavalle, Philippe

    2011-01-01

    In order to improve implant success rate, it is important to enhance their responsiveness to the prevailing conditions following implantation. Uncontrolled movement of inflammatory cells and fibroblasts is one of these in vivo problems and the porosity properties of the implant have a strong effect on these. Here, we describe a hybrid system composed of a macroporous titanium structure filled with a microporous biodegradable polymer. This polymer matrix has a distinct porosity gradient to accommodate different cell types (fibroblasts and epithelial cells). The main clinical application of this system will be the prevention of restenosis due to excessive fibroblast migration and proliferation in the case of tracheal implants. Methodology/Principal Findings A microbead-based titanium template was filled with a porous Poly (L-lactic acid) (PLLA) body by freeze-extraction method. A distinct porosity difference was obtained between the inner and outer surfaces of the implant as characterized by image analysis and Mercury porosimetry (9.8±2.2 µm vs. 36.7±11.4 µm, p≤0.05). On top, a thin PLLA film was added to optimize the growth of epithelial cells, which was confirmed by using human respiratory epithelial cells. To check the control of fibroblast movement, PKH26 labeled fibroblasts were seeded onto Titanium and Titanium/PLLA implants. The cell movement was quantified by confocal microscopy: in one week cells moved deeper in Ti samples compared to Ti/PLLA. Conclusions In vitro experiments showed that this new implant is effective for guiding different kind of cells it will contact upon implantation. Overall, this system would enable spatial and temporal control over cell migration by a gradient ranging from macroporosity to nanoporosity within a tracheal implant. Moreover, mechanical properties will be dependent mainly on the titanium frame. This will make it possible to create a polymeric environment which is suitable for cells without the need to meet mechanical

  4. A Review on Recent Advances in Stabilizing Peptides/Proteins upon Fabrication in Hydrogels from Biodegradable Polymers.

    Science.gov (United States)

    Raza, Faisal; Zafar, Hajra; Zhu, Ying; Ren, Yuan; -Ullah, Aftab; Khan, Asif Ullah; He, Xinyi; Han, Han; Aquib, Md; Boakye-Yiadom, Kofi Oti; Ge, Liang

    2018-01-18

    Hydrogels evolved as an outstanding carrier material for local and controlled drug delivery that tend to overcome the shortcomings of old conventional dosage forms for small drugs (NSAIDS) and large peptides and proteins. The aqueous swellable and crosslinked polymeric network structure of hydrogels is composed of various natural, synthetic and semisynthetic biodegradable polymers. Hydrogels have remarkable properties of functionality, reversibility, sterilizability, and biocompatibility. All these dynamic properties of hydrogels have increased the interest in their use as a carrier for peptides and proteins to be released slowly in a sustained manner. Peptide and proteins are remarkable therapeutic agents in today's world that allow the treatment of severe, chronic and life-threatening diseases, such as diabetes, rheumatoid arthritis, hepatitis. Despite few limitations, hydrogels provide fine tuning of proteins and peptides delivery with enormous impact in clinical medicine. Novels drug delivery systems composed of smart peptides and molecules have the ability to drive self-assembly and form hydrogels at physiological pH. These hydrogels are significantly important for biological and medical fields. The primary objective of this article is to review current issues concerned with the therapeutic peptides and proteins and impact of remarkable properties of hydrogels on these therapeutic agents. Different routes for pharmaceutical peptides and proteins and superiority over other drugs candidates are presented. Recent advances based on various approaches like self-assembly of peptides and small molecules to form novel hydrogels are also discussed. The article will also review the literature concerning the classification of hydrogels on a different basis, polymers used, "release mechanisms" their physical and chemical characteristics and diverse applications.

  5. Dispersion of nano-sized hydrophilic silica particles into various hydrophobic polymer networks.

    Science.gov (United States)

    Tanahashi, Mitsuru; Takeda, Kunihiko

    2014-04-01

    Dispersion of fine silica particles with hydrophilic surfaces to the hydrophobic polymer network has been investigated. Strength-controlled agglomerates of silica particles with 190 nm diameter were prepared, and they were blended with some polymers in an intensive mixer. Through the shear breakdown of the silica agglomerates in the kneaded polymer melts, the isolated primary silica nanoparticles with hydrophilic surfaces were dispersed uniformly into polycarbonate, as well as poly(ethylene-ran-vinylalcohol), polystyrene, and poly(tetrafluoroethylene-co-perfluoropropylvinylether) selected as a matrix polymer in the authors' previous studies. Unexpected result was the well dispersion of the hydrophilic silica particles into hydrophobic polymers. Taking the extremely hydrophobic perfluoropolymer as an example, the reason why silica particles can disperse into a hydrophobic polymer was also discussed by comparing the quite short-range (polymer melt with that between silica nanoparticles calculated on the assumption that the agglomerate is peeling off at the shear breakdown stage. The main finding of this study is that the attractive silica-perfluoropolymer interaction may exceed the silica-silica interaction under the special condition where the perfluoropolymer chains wind about the silica surfaces in nano-areas (less than 1% of the whole surface area of the silica particle), resulting in the well dispersion of nano-silica into the perfluoropolymer.

  6. Motion of Adsorbed Nano-Particles on Azobenzene Containing Polymer Films

    Directory of Open Access Journals (Sweden)

    Sarah Loebner

    2016-12-01

    Full Text Available We demonstrate in situ recorded motion of nano-objects adsorbed on a photosensitive polymer film. The motion is induced by a mass transport of the underlying photoresponsive polymer material occurring during irradiation with interference pattern. The polymer film contains azobenzene molecules that undergo reversible photoisomerization reaction from trans- to cis-conformation. Through a multi-scale chain of physico-chemical processes, this finally results in the macro-deformations of the film due to the changing elastic properties of polymer. The topographical deformation of the polymer surface is sensitive to a local distribution of the electrical field vector that allows for the generation of dynamic changes in the surface topography during irradiation with different light interference patterns. Polymer film deformation together with the motion of the adsorbed nano-particles are recorded using a homemade set-up combining an optical part for the generation of interference patterns and an atomic force microscope for acquiring the surface deformation. The particles undergo either translational or rotational motion. The direction of particle motion is towards the topography minima and opposite to the mass transport within the polymer film. The ability to relocate particles by photo-induced dynamic topography fluctuation offers a way for a non-contact simultaneous manipulation of a large number of adsorbed particles just in air at ambient conditions.

  7. Biodegradable and biocompatible cationic polymer delivering microRNA-221/222 promotes nerve regeneration after sciatic nerve crush.

    Science.gov (United States)

    Song, Jialin; Li, Xueyang; Li, Yingli; Che, Junyi; Li, Xiaoming; Zhao, Xiaotian; Chen, Yinghui; Zheng, Xianyou; Yuan, Weien

    2017-01-01

    MicroRNA (miRNA) has great potential to treat a wide range of illnesses by regulating the expression of eukaryotic genes. Biomaterials with high transfection efficiency and low toxicity are needed to deliver miRNA to target cells. In this study, a biodegradable and biocompatible cationic polymer (PDAPEI) was synthetized from low molecular weight polyethyleneimine (PEI1.8kDa) cross-linked with 2,6-pyridinedicarboxaldehyde. PDAPEI showed a lower cytotoxicity and higher transfection efficiency than PEI25kDa in transfecting miR-221/222 into rat Schwann cells (SCs). The upregulation of miR-221/222 in SCs promoted the expression of nerve growth factor and myelin basic protein in vitro. The mouse sciatic nerve crush injury model was used to evaluate the effectiveness of PDAPEI/miR-221/222 complexes for nerve regeneration in vivo. The results of electrophysiological tests, functional assessments, and histological and immunohistochemistry analyses demonstrated that PDAPEI/miR-221/222 complexes significantly promoted nerve regeneration after sciatic nerve crush, specifically enhancing remyelination. All these results show that the use of PDAPEI to deliver miR-221/222 may provide a safe therapeutic means of treating nerve crush injury and may help to overcome the barrier of biomaterial toxicity and low efficiency often encountered during medical intervention.

  8. Novel meloxicam releasing electrospun polymer/ceramic reinforced biodegradable membranes for periodontal regeneration applications.

    Science.gov (United States)

    Yar, Muhammad; Farooq, Ariba; Shahzadi, Lubna; Khan, Abdul Samad; Mahmood, Nasir; Rauf, Abdul; Chaudhry, Aqif Anwar; Rehman, Ihtesham Ur

    2016-07-01

    Periodontal disease is associated with the destruction of periodontal tissues, along with other disorders/problems including inflammation of tissues and severe pain. This paper reports the synthesis of meloxicam (MX) immobilized biodegradable chitosan (CS)/poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) based electrospun (e-spun) fibers and films. Electrospinning was employed to produce drug loaded fibrous mats, whereas films were generated by solvent casting method. In-vitro drug release from materials containing varying concentrations of MX revealed that the scaffolds containing higher amount of drug showed comparatively faster release. During initial first few hours fast release was noted from membranes and films; however after around 5h sustained release was achieved. The hydrogels showed good swelling property, which is highly desired for soft tissue engineered implants. To investigate the biocompatibility of our synthesized materials, VERO cells (epithelial cells) were selected and cell culture results showed that these all materials were non-cytotoxic and also these cells were very well proliferated on these synthesized scaffolds. These properties along with the anti-inflammatory potential of our fabricated materials suggest their effective utilization in periodontital treatments. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Meta-Analysis of Randomized Clinical Trials Comparing Biodegradable Polymer Drug-Eluting Stent to Second-Generation Durable Polymer Drug-Eluting Stents.

    Science.gov (United States)

    El-Hayek, Georges; Bangalore, Sripal; Casso Dominguez, Abel; Devireddy, Chandan; Jaber, Wissam; Kumar, Gautam; Mavromatis, Kreton; Tamis-Holland, Jacqueline; Samady, Habib

    2017-03-13

    The authors sought to perform a meta-analysis of randomized clinical trials (RCTs) comparing the safety and efficacy of biodegradable polymer drug-eluting stents (BP-DES) to second-generation durable polymer drug-eluting stents (DP-DES). Prior meta-analyses have established the superiority of BP-DES over bare-metal stents and first-generation DP-DES; however, their advantage compared with second-generation DP-DES remains controversial. The authors searched PubMed and Scopus databases for RCTs comparing BP-DES to the second-generation DP-DES. Outcomes included target vessel revascularization (TVR) as efficacy outcome and cardiac death, myocardial infarction (MI), and definite or probable stent thrombosis (ST) as safety outcomes. In addition, we performed landmark analysis for endpoints beyond 1 year of follow-up and a subgroup analysis based on the stent characteristics. The authors included 16 RCTs comprising 19,886 patients in the meta-analysis. At the longest available follow-up (mean duration 26 months), we observed no significant differences in TVR (p = 0.62), cardiac death (p = 0.46), MI (p = 0.98), or ST (risk ratio: 0.83, 95% confidence interval: 0.64 to 1.09; p = 0.19). Our landmark analysis showed that BP-DES were not associated with a reduction in the risk of very late ST (risk ratio: 0.87, 95% confidence interval: 0.49 to 1.53; p = 0.62). Similar outcomes were seen regardless of the eluting drug (biolimus vs. sirolimus), the stent platform (stainless steel vs. alloy), the kinetics of polymer degradation or drug release (6 months), the strut thickness of the BP-DES (thin 100 μm), or the DAPT duration (≥6 months vs. ≥12 months). BP-DES have similar safety and efficacy profiles to second-generation DP-DES. Published by Elsevier Inc.

  10. Biodegradable Kojic Acid-Based Polymers: Controlled Delivery of Bioactives for Melanogenesis Inhibition.

    Science.gov (United States)

    Faig, Jonathan J; Moretti, Alysha; Joseph, Laurie B; Zhang, Yingyue; Nova, Mary Joy; Smith, Kervin; Uhrich, Kathryn E

    2017-02-13

    Kojic acid (KA) is a naturally occurring fungal metabolite that is utilized as a skin-lightener and antibrowning agent owing to its potent tyrosinase inhibition activity. While efficacious, KA's inclination to undergo pH-mediated, thermal-, and photodegradation reduces its efficacy, necessitating stabilizing vehicles. To minimize degradation, poly(carbonate-esters) and polyesters comprised of KA and natural diacids were prepared via solution polymerization methods. In vitro hydrolytic degradation analyses revealed KA release was drastically influenced by polymer backbone composition (e.g., poly(carbonate-ester) vs polyester), linker molecule (aliphatic vs heteroatom-containing), and release conditions (physiological vs skin). Tyrosinase inhibition assays demonstrated that aliphatic KA dienols, the major degradation product under skin conditions, were more potent then KA itself. All dienols were found to be less toxic than KA at all tested concentrations. Additionally, the most lipophilic dienols were statistically more effective than KA at inhibiting melanin biosynthesis in cells. These KA-based polymer systems deliver KA analogues with improved efficacy and cytocompatible profiles, making them ideal candidates for sustained topical treatments in both medical and personal care products.

  11. 25th Anniversary Article: Polymer-Particle Composites: Phase Stability and Applications in Electrochemical Energy Storage

    KAUST Repository

    Srivastava, Samanvaya

    2013-12-09

    Polymer-particle composites are used in virtually every field of technology. When the particles approach nanometer dimensions, large interfacial regions are created. In favorable situations, the spatial distribution of these interfaces can be controlled to create new hybrid materials with physical and transport properties inaccessible in their constituents or poorly prepared mixtures. This review surveys progress in the last decade in understanding phase behavior, structure, and properties of nanoparticle-polymer composites. The review takes a decidedly polymers perspective and explores how physical and chemical approaches may be employed to create hybrids with controlled distribution of particles. Applications are studied in two contexts of contemporary interest: battery electrolytes and electrodes. In the former, the role of dispersed and aggregated particles on ion-transport is considered. In the latter, the polymer is employed in such small quantities that it has been historically given titles such as binder and carbon precursor that underscore its perceived secondary role. Considering the myriad functions the binder plays in an electrode, it is surprising that highly filled composites have not received more attention. Opportunities in this and related areas are highlighted where recent advances in synthesis and polymer science are inspiring new approaches, and where newcomers to the field could make important contributions. Polymer-particle composites are used in virtually every field of technology. When the particles approach nanometer dimensions, large interfacial regions are created that can be exploited for applications. The fundamental approaches and bottom-up synthesis strategies for understanding and controlling nanoparticle dispersion in polymers are reviewed. Applications of these approaches for creating polymer-particle composite electrolytes and electrodes for energy storage are also considered. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Simple and cost-effective fabrication of solid biodegradable polymer microneedle arrays with adjustable aspect ratio for transdermal drug delivery using acupuncture microneedles

    International Nuclear Information System (INIS)

    Cha, Kyoung Je; Kim, Taewan; Park, Sung Jea; Kim, Dong Sung

    2014-01-01

    Polymer microneedle arrays (MNAs) have received much attention for their use in transdermal drug delivery and microneedle therapy systems due to the advantages they offer, such as low cost, good mechanical properties, and a versatile choice of materials. Here, we present a simple and cost-effective method for the fabrication of a biodegradable polymer MNA in which the aspect ratio of each microneedle is adjustable using commercially available acupuncture microneedles. In our process, a master template with acupuncture microneedles, whose shape will be the final MNA, was carefully prepared by fixing them onto a plastic substrate with selectively drilled holes which, in turn, determine the aspect ratios of the microneedles. A polylactic acid (PLA; a biodegradable polymer) MNA was fabricated by a micromolding process with a polydimethylsiloxane (PDMS) mold containing the cavity of the microneedles, which was obtained by the PDMS replica molding against the master template. The mechanical force and degradation behavior of the replicated PLA MNA were characterized with the help of a compression test and an accelerated degradation test, respectively. Finally, the transdermal drug delivery performance of the PLA MNA was successfully simulated by two different methods of penetration and staining, using the skin of a pig cadaver. These results indicated that the proposed method can be effectively used for the fabrication of polymer MNAs which can be used in various microneedle applications. (paper)

  13. Simple and cost-effective fabrication of solid biodegradable polymer microneedle arrays with adjustable aspect ratio for transdermal drug delivery using acupuncture microneedles

    Science.gov (United States)

    Cha, Kyoung Je; Kim, Taewan; Jea Park, Sung; Kim, Dong Sung

    2014-11-01

    Polymer microneedle arrays (MNAs) have received much attention for their use in transdermal drug delivery and microneedle therapy systems due to the advantages they offer, such as low cost, good mechanical properties, and a versatile choice of materials. Here, we present a simple and cost-effective method for the fabrication of a biodegradable polymer MNA in which the aspect ratio of each microneedle is adjustable using commercially available acupuncture microneedles. In our process, a master template with acupuncture microneedles, whose shape will be the final MNA, was carefully prepared by fixing them onto a plastic substrate with selectively drilled holes which, in turn, determine the aspect ratios of the microneedles. A polylactic acid (PLA; a biodegradable polymer) MNA was fabricated by a micromolding process with a polydimethylsiloxane (PDMS) mold containing the cavity of the microneedles, which was obtained by the PDMS replica molding against the master template. The mechanical force and degradation behavior of the replicated PLA MNA were characterized with the help of a compression test and an accelerated degradation test, respectively. Finally, the transdermal drug delivery performance of the PLA MNA was successfully simulated by two different methods of penetration and staining, using the skin of a pig cadaver. These results indicated that the proposed method can be effectively used for the fabrication of polymer MNAs which can be used in various microneedle applications.

  14. Biodegradable polymer Biolimus-eluting stent (Nobori® for the treatment of coronary artery lesions: review of concept and clinical results

    Directory of Open Access Journals (Sweden)

    Schurtz G

    2014-02-01

    Full Text Available Guillaume Schurtz,1,2 Cédric Delhaye,1 Christopher Hurt,1,2 Henri Thieuleux,1,2 Gilles Lemesle1–3 1Centre Hémodynamique et Unité des Soins Intensifs de Cardiologie, Hôpital Cardiologique, Centre Hospitalier Régional et Universitaire de Lille, Lille, France; 2Faculté de Médecine de Lille, Lille, France; 3Unité INSERM UMR744, Institut Pasteur de Lille, Lille, France Abstract: First-generation drug-eluting stents have raised concerns regarding the risk of late and very late stent thrombosis compared with bare metal stents and require prolonged dual antiplatelet therapy. Despite extensive investigations, the physiopathology of these late events remains incompletely understood. Aside from patient- and lesion-related risk factors, stent polymer has been cited as one of the potential causes. In fact, the persistence of durable polymer after complete drug release has been shown to be responsible for local hypersensitivity and inflammatory reactions. Third-generation drug-eluting stents with more biocompatible or biodegradable polymers have subsequently been developed to address this problem. In this article, we evaluate and discuss the concept and clinical results (safety and efficacy of a third-generation drug-eluting stent with biodegradable polymer: the Nobori® stent. Keywords: percutaneous coronary intervention, stent thrombosis, antiplatelet therapy

  15. Impact Resistance Enhancement by Adding Core-Shell Particle to Epoxy Resin Modified with Hyperbranched Polymer

    Directory of Open Access Journals (Sweden)

    Shuiping Li

    2017-12-01

    Full Text Available A core-shell particle was fabricated by grafting amino-terminated hyperbranched polymer to the surface of silica nanoparticles. The influences of core-shell particle contents on the tensile and impact strength of the epoxy thermosets modified with amino-terminated hyperbranched polymer were discussed in detail. For comparison, core-shell particle was added into the epoxy/polyamide system for toughness improvement. Results from tensile and impact tests are provided. The introduction of core-shell particle into the epoxy/polyamide systems just slightly enhanced the tensile and impact strength. The incorporation of 3 wt % core-shell particle could substantially improve the tensile and impact strength of epoxy/amino-terminated hyperbranched polymer thermosets. Field emission-scanning electron microscope images of the impact fracture surfaces showed that the excellent impact resistance of epoxy/amino-terminated hyperbranched polymer/core-shell particle thermosets may be attributed to the synergistic effect of shearing deformation and crack pinning/propagation, which is induced by the good compatibility between epoxy matrix and core-shell particle in the presence of amino-terminated hyperbranched polymer.

  16. Restrictions in Model Reduction for Polymer Chain Models in Dissipative Particle Dynamics

    KAUST Repository

    Moreno Chaparro, Nicolas

    2014-06-06

    We model high molecular weight homopolymers in semidilute concentration via Dissipative Particle Dynamics (DPD). We show that in model reduction methodologies for polymers it is not enough to preserve system properties (i.e., density ρ, pressure p, temperature T, radial distribution function g(r)) but preserving also the characteristic shape and length scale of the polymer chain model is necessary. In this work we apply a DPD-model-reduction methodology for linear polymers recently proposed; and demonstrate why the applicability of this methodology is limited upto certain maximum polymer length, and not suitable for solvent coarse graining.

  17. Ultra low density biodegradable shape memory polymer foams with tunable physical properties

    Energy Technology Data Exchange (ETDEWEB)

    Singhal, Pooja; Wilson, Thomas S.; Cosgriff-Hernandez, Elizabeth; Maitland, Duncan J.

    2017-12-12

    Compositions and/or structures of degradable shape memory polymers (SMPs) ranging in form from neat/unfoamed to ultra low density materials of down to 0.005 g/cc density. These materials show controllable degradation rate, actuation temperature and breadth of transitions along with high modulus and excellent shape memory behavior. A method of m ly low density foams (up to 0.005 g/cc) via use of combined chemical and physical aking extreme blowing agents, where the physical blowing agents may be a single compound or mixtures of two or more compounds, and other related methods, including of using multiple co-blowing agents of successively higher boiling points in order to achieve a large range of densities for a fixed net chemical composition. Methods of optimization of the physical properties of the foams such as porosity, cell size and distribution, cell openness etc. of these materials, to further expand their uses and improve their performance.

  18. Pinosylvin-Based Polymers: Biodegradable Poly(Anhydride-Esters) for Extended Release of Antibacterial Pinosylvin.

    Science.gov (United States)

    Bien-Aime, Stephan; Yu, Weiling; Uhrich, Kathryn E

    2016-07-01

    Pinosylvin is a natural stilbenoid known to exhibit antibacterial bioactivity against foodborne bacteria. In this work, pinosylvin is chemically incorporated into a poly(anhydride-ester) (PAE) backbone via melt-condensation polymerization, and characterized with respect to its physicochemical and thermal properties. In vitro release studies demonstrate that pinosylvin-based PAEs hydrolytically degrade over 40 d to release pinosylvin. Pseudo-first order kinetic experiments on model compounds, butyric anhydride and 3-butylstilbene ester, indicate that the anhydride linkages hydrolyze first, followed by the ester bonds to ultimately release pinosylvin. An antibacterial assay shows that the released pinosylvin exhibit bioactivity, while in vitro cytocompatibility studies demonstrate that the polymer is noncytotoxic toward fibroblasts. These preliminary findings suggest that the pinosylvin-based PAEs can serve as food preservatives in food packaging materials by safely providing antibacterial bioactivity over extended time periods. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Dielectric properties of polymer-particle nanocomposites influenced by electronic nature of filler surfaces.

    Science.gov (United States)

    Siddabattuni, Sasidhar; Schuman, Thomas P; Dogan, Fatih

    2013-03-01

    The interface between the polymer and the particle has a critical role in altering the properties of a composite dielectric. Polymer-ceramic nanocomposites are promising dielectric materials for many electronic and power devices, combining the high dielectric constant of ceramic particles with the high dielectric breakdown strength of a polymer. Self-assembled monolayers of electron rich or electron poor organophosphate coupling groups were applied to affect the filler-polymer interface and investigate the role of this interface on composite behavior. The interface has potential to influence dielectric properties, in particular the leakage and breakdown resistance. The composite films synthesized from the modified filler particles dispersed into an epoxy polymer matrix were analyzed by dielectric spectroscopy, breakdown strength, and leakage current measurements. The data indicate that significant reduction in leakage currents and dielectric losses and improvement in dielectric breakdown strengths resulted when electropositive phenyl, electron-withdrawing functional groups were located at the polymer-particle interface. At a 30 vol % particle concentration, dielectric composite films yielded a maximum energy density of ~8 J·cm(-3) for TiO2-epoxy nanocomposites and ~9.5 J·cm(-3) for BaTiO3-epoxy nanocomposites.

  20. Dynamic yielding, shear thinning, and stress rheology of polymer-particle suspensions and gels.

    Science.gov (United States)

    Kobelev, Vladimir; Schweizer, Kenneth S

    2005-10-22

    The nonlinear rheological version of our barrier hopping theory for particle-polymer suspensions and gels has been employed to study the effect of steady shear and constant stress on the alpha relaxation time, yielding process, viscosity, and non-Newtonian flow curves. The role of particle volume fraction, polymer-particle size asymmetry ratio, and polymer concentration have been systematically explored. The dynamic yield stress decreases in a polymer-concentration- and volume-fraction-dependent manner that can be described as apparent power laws with effective exponents that monotonically increase with observation time. Stress- or shear-induced thinning of the viscosity becomes more abrupt with increasing magnitude of the quiescent viscosity. Flow curves show an intermediate shear rate dependence of an effective power-law form, becoming more solidlike with increasing depletion attraction. The influence of polymer concentration, particle volume fraction, and polymer-particle size asymmetry ratio on all properties is controlled to a first approximation by how far the system is from the gelation boundary of ideal mode-coupling theory (MCT). This emphasizes the importance of the MCT nonergodicity transition despite its ultimate destruction by activated barrier hopping processes. Comparison of the theoretical results with limited experimental studies is encouraging.

  1. Production methods and stabilization strategies for polymer-based nanoparticles and microparticles for parenteral delivery of peptides and proteins

    NARCIS (Netherlands)

    Teekamp, Naomi; Duque, Luisa F.; Frijlink, Henderik W; Hinrichs, Wouter Lj; Olinga, Peter

    2015-01-01

    Introduction: Therapeutic proteins and peptides often require parenteral administration, which compels frequent administration and patient discomfort. This ultimately decreases compliance and leads to therapy failure. Biocompatible and biodegradable polymers offer a versatile matrix for particles

  2. PREPARATION AND CHARACTERIZATION OF BIODEGRADABLE ...

    African Journals Online (AJOL)

    Dr Abdusalam

    Keywords: Starch, Acetylation, Biodegradation, Poly(vinyl alcohol), Polymer blend. INTRODUCTION. Non-biodegradable polymers, such as polyethene, polypropane, poly(vinylchloride) etc have excellent mechanical properties such as tensile strength, tensile strain, bursting strength and tear strength (Hay and. Sharma.

  3. Solid-liquid two-phase partitioning bioreactors (TPPBs) operated with waste polymers. Case study: 2,4-dichlorophenol biodegradation with used automobile tires as the partitioning phase.

    Science.gov (United States)

    Tomei, M Concetta; Annesini, M Cristina; Daugulis, Andrew J

    2012-11-01

    Used automobile tire pieces were tested for their suitability as the sequestering phase in a two-phase partitioning bioreactor to treat 2,4-dichlorophenol (DCP). Abiotic sorption tests and equilibrium partitioning tests confirmed that tire "crumble" possesses very favourable properties for this application with DCP diffusivity (4.8 × 10(-8) cm(2)/s) and partition coefficient (31) values comparable to those of commercially available polymers. Biodegradation tests further validated the effectiveness of using waste tires to detoxify a DCP solution, and allow for enhanced biodegradation compared to conventional single-phase operation. These results establish the potential of using a low-cost waste material to assist in the bioremediation of a toxic aqueous contaminant.

  4. Biodegradable polymer drug-eluting stents versus first-generation durable polymer drug-eluting stents: A systematic review and meta-analysis of 12 randomized controlled trials.

    Science.gov (United States)

    Bundhun, Pravesh Kumar; Pursun, Manish; Huang, Feng

    2017-11-01

    Even if drug-eluting stents (DES) showed beneficial effects in patients with coronary artery diseases (CADs), limitations have been observed with the first-generation durable polymer DES (DP-DES). Recently, biodegradable polymer DES (BP-DES) have been approved to be used as an alternative to DP-DES, with potential benefits. We aimed to systematically compare BP-DES with the first-generation DP-DES using a large number of randomized patients. Electronic databases were searched for randomized controlled trials (RCTs) comparing BP-DES with first-generation DP-DES. The main endpoints were the long-term (≥2 years) adverse clinical outcomes that were reported with these 2 types of DES. We calculated odds ratios (ORs) with 95% confidence intervals (CIs) and the analysis was carried out by RevMan 5.3 software. Twelve trials with a total number of 13,480 patients (7730 and 5750 patients were treated by BP-DES and first-generation DP-DES, respectively) were included. During a long-term follow-up period of ≥2 years, mortality, myocardial infarction (MI), target lesion revascularization (TLR), and major adverse cardiac events (MACEs) were not significantly different between these 2 groups with OR: 0.84, 95% CI: 0.66-1.07; P = .16, I = 0%, OR: 1.01, 95% CI: 0.45-2.27; P = .98, I = 0%, OR: 0.91, 95% CI: 0.75-1.11; P = .37, I = 0% and OR: 0.86, 95% CI: 0.44-1.67; P = .65, I = 0%, respectively. Long-term total stent thrombosis (ST), definite ST, and probable ST were also not significantly different between BP-DES and the first-generation DP-DES with OR: 0.77, 95% CI: 0.50-1.18; P = .22, I = 0%, OR: 0.71, 95% CI: 0.43-1.18; P = .19, I = 0% and OR: 1.31, 95% CI: 0.56-3.08; P = .53, I = 6%, respectively. Long-term mortality, MI, TLR, MACEs, and ST were not significantly different between BP-DES and the first-generation DP-DES. However, the follow-up period was restricted to only 3 years in this analysis. Copyright © 2017

  5. Polymer degradation and ultrafine particles - Potential inhalation hazards for astronauts

    Science.gov (United States)

    Ferin, J.; Oberdoerster, G.

    1992-01-01

    To test the hypothesis that exposure to ultrafine particles results in an increased interstiatilization of the particles which is accompanied by an acute pathological inflammation, rats were exposed to titanium dioxide (TiO2) particles by intratracheal instillation and by inhalation. Both acute intratracheal instillation and subchronic inhalation studies on rats show that ultrafine TiO2 particles access the pulmonary interstitium to a larger extent than fine particles and that they elicit an inflammatory response as indicated by PMN increase in lavaged cells. The release of ultrafine particles into the air of an enclosed environment from a thermodegradation event or from other sources is a potential hazard for astronauts. Knowing the mechanisms of action is a prerequisite for technical or medical countermeasures.

  6. Radiation crosslinking of polymers with segregated metallic particles. Final report, June 1, 1971--September 30, 1973

    International Nuclear Information System (INIS)

    Corneliussen, R.D.; Kamel, I.; Kusy, R.P.

    1973-01-01

    Through the past four years of research, a new approach to fabricating conductive polymer/metal composites has been developed. This approach consists of compacting mixtures of polymer and metal powders and then stabilizing the composite through radiation-induced crosslinking. The result is a mechanically strong, conductive materials consisting of two intertwining networks. One is a massive network consisting of fused crosslinked, large (greater than 100 μ) polymer particles while the other is a fine network of small, metallic particles (greater than 10 μ). Nine different systems including crystalline, amorphous, and rubbery polymers were studied. Processing at this time is limited to compression molding in a closed die because of network stability problems. Costs for processing were estimated at about $6.00/lb compared to $50.00 and up for commercial material based on random networks. (U.S.)

  7. Pore Structure of Macroporous Polymers Using Polystyrene/Silica Composite Particles as Pickering Stabilizers.

    Science.gov (United States)

    Tu, Shuhua; Zhu, Chenxu; Zhang, Lingyun; Wang, Haitao; Du, Qiangguo

    2016-12-13

    A novel approach for the preparation of interconnected macroporous polymers with a controllable pore structure was reported. The method was based on the polymerization of water-in-oil Pickering high internal phase emulsion (HIPE) stabilized by polystyrene (PS)/silica composite particles. The composite Pickering stabilizers were facilely obtained by mixing positively charged PS microspheres and negatively charged silica nanoparticles, and their amphiphilicity could be delicately tailored by varying the ratio of PS and silica. The droplet size of Pickering HIPEs was characterized using an optical microscope. The pore structure of polymer foams was observed using a scanning electron microscope. The interconnectivity of macroporous polymers was evaluated upon their gas permeability, which was greatly improved after etching PS microspheres included in the Pickering stabilizers with tetrahydrofuran. As a result, fine tailoring of the pore structure of polymer foams could be realized by simply tuning the ratio of PS to silica particles in the composite stabilizer.

  8. Morphological analysis of polymer systems with broad particle size distribution

    Czech Academy of Sciences Publication Activity Database

    Šlouf, Miroslav; Ostafinska, Aleksandra; Nevoralová, Martina; Fortelný, Ivan

    2015-01-01

    Roč. 42, April (2015), s. 8-16 ISSN 0142-9418 R&D Projects: GA ČR(CZ) GA14-17921S Institutional support: RVO:61389013 Keywords : polymer blends * morphology * image analysis Subject RIV: JJ - Other Materials Impact factor: 2.350, year: 2015

  9. Effect of ion beam irradiation on metal particle doped polymer ...

    Indian Academy of Sciences (India)

    that the surface roughness increases after ion beam irradiation. Keywords. Composite materials; ion beam irradiation; dielectric properties; X-ray diffraction. 1. Introduction. Various metal fillers were incorporated in polymers to pro- duce novel functionalized composites, which have found extensive applications, such as ...

  10. Micron-sized polymer particles from Tanzanian cashew nut shell

    African Journals Online (AJOL)

    a

    While petrochemicals cannot be sustained as they become either expensive or highly depleted leading to economical and environmental problems, natural products are renewable. Thus, it is necessary for the polymer industry to look for renewable monomer sources and cashew nut shell liquid (CNSL) is one of the natural ...

  11. Self-assembly of biodegradable copolyester and reactive HPMA-based polymers into nanoparticles as an alternative stealth drug delivery system

    Czech Academy of Sciences Publication Activity Database

    Jäger, Eliezer; Jäger, Alessandro; Etrych, Tomáš; Giacomelli, F. C.; Chytil, Petr; Jigounov, Alexander; Putaux, J.-L.; Říhová, Blanka; Ulbrich, Karel; Štěpánek, Petr

    2012-01-01

    Roč. 8, č. 37 (2012), s. 9563-9575 ISSN 1744-683X R&D Projects: GA AV ČR IAAX00500803; GA ČR GAP208/10/1600 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z50200510 Institutional support: RVO:61389013 ; RVO:61388971 Keywords : biodegradable nanoparticles * light scattering from polymer nanoparticles * doxorubicin drug release Subject RIV: CF - Physical ; Theoretical Chemistry; EC - Immunology (MBU-M) Impact factor: 3.909, year: 2012

  12. Synthesis, characterization and biocompatibility of novel biodegradable cross-linked co-polymers based on poly(propylene oxide) diglycidylether and polyethylenimine.

    Science.gov (United States)

    Ding, Yunsheng; Wang, Jing; Wong, Cynthia S; Halley, Peter J; Guo, Qipeng

    2011-01-01

    Novel biodegradable cross-linked co-polymers were prepared from poly(propylene glycol) diglycidylether (PPGDGE) and poly(ethylene imine) (PEI). PPGDGE and PEI were mixed at ambient temperature with varying PEI concentrations of 10, 15, 18.5, 25, 30, 40 and 50 wt%; the homogenous PPGDGE/PEI mixtures obtained were cured at elevated temperatures, resulting in formation of PPG-PEI cross-linked co-polymers via ring-opening reaction of PPGDGE with PEI. The physicochemical and biological properties of these co-polymers were dependent on the PEI content and the extent of curing reaction. The glass transition temperature of PPG-PEI cross-linked co-polymers varied in the range from -14 to +42°C, while the co-polymers displayed composition-dependent mechanical behavior, from brittle to ductile with increasing PEI content from 18.5 wt% to 40 wt%. Chinese hamster ovary (CHO) cells were cultured on the PPG-PEI co-polymers; the MTT assay was used to measure cell viability and determine the cytotoxicity. The cell viability rate, relative to tissue-culture polystyrene (TCPS), increased from 49% to 125% with increasing PEI content from 18.5 wt% to 40 wt%. Although epoxy monomers usually exhibit cytotoxicity, the epoxy groups were exhausted via curing reaction in the fully cross-linked co-polymers. The PEI-cured PPG epoxy resin, i.e., PPG-PEI cross-linked co-polymers obtained in this study, showed excellent biocompatibility.

  13. The synthesis and characterization of water-reducible nanoscale Colloidal Unimolecular Polymer (CUP) particles

    Science.gov (United States)

    Riddles, Cynthia Jeannette

    The coatings industry has adapted to more stringent guidelines in paint formulations. Current VOC (volatile organic compound) limits placed by the federal government have pushed the industry toward the development of paint formulations which have very little to no VOC's. The development of Colloidal Unimolecular Polymer (CUP) particles is a step in the direction of providing a resin system which exists in zero VOC aqueous dispersion. The CUP particles are a part of the polymer field of Single Chain Nano Particles (SCNP) and ranged in diameters of 3-9 nm. The research presented in this dissertation describes the synthesis and design of these particles along with the various means of instrumentation used to gain insight into the structure and nature of these particles when suspended in aqueous medium.

  14. Universal shape characteristics for the mesoscopic star-shaped polymer via dissipative particle dynamics simulations

    OpenAIRE

    Kalyuzhnyi, O.; Ilnytskyi, J. M.; Holovatch, Yu.; von Ferber, C.

    2017-01-01

    In this paper we study the shape characteristics of star-like polymers in various solvent quality using a mesoscopic level of modeling. The dissipative particle dynamics simulations are performed for the homogeneous and four different heterogeneous star polymers with the same molecular weight. We analyse the gyration radius and asphericity at the bad, good and $\\theta$-solvent regimes. Detailed explanation based on interplay between enthalpic and entropic contributions to the free energy and ...

  15. Design of sustained release fine particles using two-step mechanical powder processing: particle shape modification of drug crystals and dry particle coating with polymer nanoparticle agglomerate.

    Science.gov (United States)

    Kondo, Keita; Ito, Natsuki; Niwa, Toshiyuki; Danjo, Kazumi

    2013-09-10

    We attempted to prepare sustained release fine particles using a two-step mechanical powder processing method; particle-shape modification and dry particle coating. First, particle shape of bulk drug was modified by mechanical treatment to yield drug crystals suitable for the coating process. Drug crystals became more rounded with increasing rotation speed, which demonstrates that powerful mechanical stress yields spherical drug crystals with narrow size distribution. This process is the result of destruction, granulation and refinement of drug crystals. Second, the modified drug particles and polymer coating powder were mechanically treated to prepare composite particles. Polymer nanoparticle agglomerate obtained by drying poly(meth)acrylate aqueous dispersion was used as a coating powder. The porous nanoparticle agglomerate has superior coating performance, because it is completely deagglomerated under mechanical stress to form fine fragments that act as guest particles. As a result, spherical drug crystals treated with porous agglomerate were effectively coated by poly(meth)acrylate powder, showing sustained release after curing. From these findings, particle-shape modification of drug crystals and dry particle coating with nanoparticle agglomerate using a mechanical powder processor is expected as an innovative technique for preparing controlled-release coated particles having high drug content and size smaller than 100 μm. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Reversible Formation of Silver Clusters and Particles in Polymer Films

    National Research Council Canada - National Science Library

    Gaddy, G. A; Korchev, A. S; McLain, Jason L; Black, J. R; Mills, German; Bratcher, Matthew S; Slaten, B. L

    2004-01-01

    .... The formation of Ag clusters and particles is monitored using UV-VIS spectroscopy. Films treated with H2O2 exhibit bleaching of the UV-VIS signals corresponding to Ag clusters and Ag particles that were generated during the photo reduction...

  17. Encapsulation of clay within polymer particles in a high-solids content aqueous dispersion.

    Science.gov (United States)

    Reyes, Yuri; Peruzzo, Pablo J; Fernández, Mercedes; Paulis, Maria; Leiza, Jose R

    2013-08-06

    By using a two-step polymerization process, it was possible to encapsulate clay platelets within polymer particles dispersed in water. First, seed polymer particles with chemically bonded clay were obtained by batch miniemulsion polymerization. Then, the clay was buried within the particles by the addition of neat monomer in a second step. The final stable dispersions can have a solids content of up to 50 wt %. Transmission electron microscopy images clearly show the presence of clay platelets inside the polymer colloids, although they are not totally exfoliated. The obtained nanocomposites showed an increase in both the storage modulus in the rubbery state and the water resistance as the clay content increases. The approach presented here might be useful for encapsulating other high-aspect ratio nanofillers.

  18. Polymer particle shape independently influences binding and internalization by macrophages.

    Science.gov (United States)

    Sharma, Gaurav; Valenta, David T; Altman, Yoav; Harvey, Sheryl; Xie, Hui; Mitragotri, Samir; Smith, Jeffrey W

    2010-11-01

    The interaction of macrophages with micro and nanoparticles (MNPs) is important because these cells clear particles from the circulation, and because they are potential therapeutic targets in inflammatory conditions, atherosclerosis and cancer. Therefore, an understanding of the features of MNPs that influence their interaction with macrophages may allow optimization of their properties for enhanced drug delivery. In this study, we show that particle shape impacts phagocytosis by macrophages, and more importantly, that particle shape and size separately impact attachment and internalization. The study provides a methodology for further exploring how particle shape can be controlled to achieve desired attachment and internalization. The results of the study also give mechanistic guidance on how particle shape can be manipulated to design drug carriers to evade macrophages, or alternatively to target macrophages. Copyright © 2010 Elsevier B.V. All rights reserved.

  19. A model for diffusion of water into a swelling particle with a free boundary: Application to a super absorbent polymer particle

    NARCIS (Netherlands)

    Sweijen, T.; van Duijn, C.J.; Hassanizadeh, S.M.

    2017-01-01

    In this work, a model is developed for describing the swelling of an individual particle, made of Super Absorbent Polymers (SAP). Governing equations for the water uptake at the particle surface, diffusion of water into the particle and the subsequent swelling of the particle are developed for an

  20. Collective magnetic behavior of biocompatible systems of maghemite particles coated with functional polymer shells

    Energy Technology Data Exchange (ETDEWEB)

    Demchenko, P.; Nedelko, N. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Mitina, N. [Lviv Polytechnic National University, 12 Bandera, Lviv 79013 (Ukraine); Lewińska, S.; Dłużewski, P. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Greneche, J.M. [Institut des Molécules et Matériaux du Mans, IMMM UMR CNRS 6283, Université du Maine, Avenue Olivier Messiaen, 72085 Le Mans (France); Ubizskii, S.; Navrotskyi, S.; Zaichenko, A. [Lviv Polytechnic National University, 12 Bandera, Lviv 79013 (Ukraine); Ślawska-Waniewska, A., E-mail: slaws@ifpan.edu.pl [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland)

    2015-04-01

    Three series of core–shell maghemite nanoparticles were prepared by a template synthesis using surface active oligoperoxides and further surface initiated grafting functional polymers, forming shell suitable for biomedical applications. Because the polymer shells prevent exchange coupling between maghemite particles, the overall magnetic properties of the samples studied are dominated by dipolar interparticle interactions. Only the sample with the highest polymer fraction displays superparamagnetic relaxation phenomena close to the room temperature. On cooling, the magnetostatic interactions lead to a disordered collective magnetic state that should be described in terms of a spin-glass phenomenology. This collective freezing cannot however be considered as a generic spin-glass phase transition at a well-defined temperature but rather as freezing to a metastable glass-like state of locally correlated structural domains (clusters) without a long-range order. A quasi static spin ordering is only achieved at temperatures much below the freezing temperature. - Highlights: • Core–shell γ-Fe{sub 2}O{sub 3}/polymer particles were prepared using new surface active oligoperoxides. • Grafting of particle shells with functional polymers, suitable for biomedical applications. • Magnetic properties of nanocomposites are dominated by dipolar interactions. • On cooling magnetostatic interactions lead to a spin-glass-like state. • The most diluted maghemite particles display superparamagnetism at 300 K.

  1. Plasma polymer-functionalized silica particles for heavy metals removal.

    Science.gov (United States)

    Akhavan, Behnam; Jarvis, Karyn; Majewski, Peter

    2015-02-25

    Highly negatively charged particles were fabricated via an innovative plasma-assisted approach for the removal of heavy metal ions. Thiophene plasma polymerization was used to deposit sulfur-rich films onto silica particles followed by the introduction of oxidized sulfur functionalities, such as sulfonate and sulfonic acid, via water-plasma treatments. Surface chemistry analyses were conducted by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy. Electrokinetic measurements quantified the zeta potentials and isoelectric points (IEPs) of modified particles and indicated significant decreases of zeta potentials and IEPs upon plasma modification of particles. Plasma polymerized thiophene-coated particles treated with water plasma for 10 min exhibited an IEP of less than 3.5. The effectiveness of developed surfaces in the adsorption of heavy metal ions was demonstrated through copper (Cu) and zinc (Zn) removal experiments. The removal of metal ions was examined through changing initial pH of solution, removal time, and mass of particles. Increasing the water plasma treatment time to 20 min significantly increased the metal removal efficiency (MRE) of modified particles, whereas further increasing the plasma treatment time reduced the MRE due to the influence of an ablation mechanism. The developed particulate surfaces were capable of removing more than 96.7% of both Cu and Zn ions in 1 h. The combination of plasma polymerization and oxidative plasma treatment is an effective method for the fabrication of new adsorbents for the removal of heavy metals.

  2. Particle-in-a-bos model of one-dimensional excitons in conjugated polymers

    DEFF Research Database (Denmark)

    Pedersen, T.G.; Johansen, P.M.; Pedersen, H.C.

    2000-01-01

    A simple two-particle model of excitons in conjugated polymers is proposed as an alternative to usual highly computationally demanding quantum chemical methods. In the two-particle model, the exciton is described as an electron-hole pair interacting via Coulomb forces and confined to the polymer...... of these cases an approximate solution for the general case is obtained. As an application of the model the influence of a static electric field on the electron-hole overlap integral and exciton energy is considered....

  3. Biodegradable large compound vesicles with controlled size prepared via the self-assembly of branched polymers in nanodroplet templates.

    Science.gov (United States)

    Wang, Long-Hai; Xu, Xiao-Man; Hong, Chun-Yan; Wu, De-Cheng; Yu, Zhi-Qiang; You, Ye-Zi

    2014-09-04

    Generally, it is very difficult to control the size of large compound vesicles. Here, we introduce a novel method for the preparation of biodegradable large compound vesicles with controlled size and narrow size distribution by using aqueous nanodroplets as templates.

  4. The Study of Starch Seeds Durian (Durio zibethinus Effect as the Filler Material on Tensile Strength and Biodegradation of Polymers Polystyrene (PS

    Directory of Open Access Journals (Sweden)

    Rifka Sudi

    2013-11-01

    Full Text Available The study of starch seeds durian (Durio zibethinus effect as the filler material on tensile strength and biodegradation of polymers polystyrene (PS  has been done. In this study, the sample was made with 5 variations of Polystyrene:Starch:glycerol as follows:(95:0:5; 90:5:5; 85:10:5; 80:15:5 and 75:20:5 %. The samples were made using the hotpress machine and the ASTM D368 standard. The mechanical properties (tensile strength were tested using a tensile tester. The testing for functional groups were using FT-IR. The surface morphology was obtained by AFM and biodegradation through burial the samples for 40 days (time of observation 1, 2, 3, 4 and 5 weeks. As the results showed that the tensile strength values are influenced by variations in the composition of composite materials. The optimum tensile strength values were obtained on samples of PS-2 (90% of PS: 5% of Starch: 5% of glycerol with a tensile strength value of 0.55 kgf / mm². Based on the analysis of functional groups, it was found that there is no chemical reaction, which is characterized by the emergence of new functional groups on the composite sample. The surface morphology observation showed that the variation does not affect the relative composition of the surface morphology of the samples. Biodegradation test results showed that the samples of PS-4 and PS-5 began degraded after burial for 4 weeks.

  5. Infinite Coordination Polymer Nano- and Micro-Particles

    Science.gov (United States)

    2015-06-12

    repeatable synthesis of relatively mono -disperse particles (i.e., size control) and the high-yielding covalent attachment of oligonucleotides to the...the DLS results. After synthesis and characterization of the mono -disperse particles, which contained pendant azide 5 moieties, oligonucleotides...the nucleus in blue, whereas the Cy5 dye attached to DNA is red. 6 processes. To test our hypothesis, cellular uptake was examined in HeLa

  6. Programming the composition of polymer blend particles for controlled immunity towards individual protein antigens.

    Science.gov (United States)

    Zhan, Xi; Shen, Hong

    2015-05-28

    In order for a more precise control over the quality and quantity of immune responses stimulated by synthetic particle-based vaccines, it is critical to control the colloidal stability of particles and the release of protein antigens in both extracellular space and intracellular compartments. Different proteins exhibit different sizes, charges and solubilities. This study focused on modulating the release and colloidal stability of proteins with varied isoelectric points. A polymer particle delivery platform made from the blend of three polymers, poly(lactic-co-glycolic acid) (PLGA) and two random pH-sensitive copolymers, were developed. Our study demonstrated its programmability with respective to individual proteins. We showed the colloidal stability of particles at neutral environment and the release of each individual protein at different pH environments were dependent on the ratio of two charge polymers. Subsequently, two antigenic proteins, ovalbumin (OVA) and Type 2 Herpes Simplex Virus (HSV-2) glycoprotein D (gD) protein, were incorporated into particles with systematically varied compositions. We demonstrated that the level of in vitro CD8(+) T cell and in vivo immune responses were dependent on the ratio of two charged polymers, which correlated well with the release of proteins. This study provided a promising design framework of pH-responsive synthetic vaccines for protein antigens of interest. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Biodegradable and biocompatible cationic polymer delivering microRNA-221/222 promotes nerve regeneration after sciatic nerve crush

    Directory of Open Access Journals (Sweden)

    Song J

    2017-06-01

    Full Text Available Jialin Song,1,2 Xueyang Li,3 Yingli Li,4,5 Junyi Che,6 Xiaoming Li,6 Xiaotian Zhao,6 Yinghui Chen,7,* Xianyou Zheng,1,* Weien Yuan6,* 1Department of Orthopedics, Shanghai Jiao Tong University Affiliated Sixth People’s Hospital, 2Department of Orthopedics, Shanghai University of Medicine and Health, Shanghai, Sixth People’s Hospital East Campus, Shanghai, 3Department of Plastic and Reconstructive Surgery, Xuzhou Medical College Affiliated Hospital, Xuzhou, Jiangsu, 4Department of Plastic Surgery, The General Hospital of Jinan Military Command, Jinan, Shandong, 5Department of Plastic Surgery, Chang Hai Hospital, Second Military Medical University, 6School of Pharmacy, Shanghai Jiao Tong University, 7Department of Neurology, Jinshan Hospital, Fudan University, JinShan District, Shanghai, People’s Republic of China *These authors contributed equally to this work Abstract: MicroRNA (miRNA has great potential to treat a wide range of illnesses by regulating the expression of eukaryotic genes. Biomaterials with high transfection efficiency and low toxicity are needed to deliver miRNA to target cells. In this study, a biodegradable and biocompatible cationic polymer (PDAPEI was synthetized from low molecular weight polyethyleneimine (PEI1.8kDa cross-linked with 2,6-pyridinedicarboxaldehyde. PDAPEI showed a lower cytotoxicity and higher transfection efficiency than PEI25kDa in transfecting miR-221/222 into rat Schwann cells (SCs. The upregulation of miR-221/222 in SCs promoted the expression of nerve growth factor and myelin basic protein in vitro. The mouse sciatic nerve crush injury model was used to evaluate the effectiveness of PDAPEI/miR-221/222 complexes for nerve regeneration in vivo. The results of electrophysiological tests, functional assessments, and histological and immunohistochemistry analyses demonstrated that PDAPEI/miR-221/222 complexes significantly promoted nerve regeneration after sciatic nerve crush, specifically enhancing

  8. A Particle Element Approach for Modelling the 3D Printing Process of Fibre Reinforced Polymer Composites

    OpenAIRE

    Yang, D; Wu, K; Wan, L; Sheng, Y

    2017-01-01

    This paper presents a new numerical approach for modelling the 3D printing process of fibre reinforced polymer composites by fused deposition modelling (FDM). The approach is based on the coupling between two particle methods, namely smoothed particle hydrodynamics (SPH) and discrete element method (DEM). The coupled SPH-DEM model has distinctive advantages in dealing with the free surface flow, large deformation of fibres, and/or fibre-fibre interaction that are involved in the FDM process. ...

  9. Nanoscale indentation of polymer and composite polymer-silica core-shell submicrometer particles by atomic force microscopy.

    Science.gov (United States)

    Armini, Silvia; Vakarelski, Ivan U; Whelan, Caroline M; Maex, Karen; Higashitani, Ko

    2007-02-13

    Atomic force microscopy was employed to probe the mechanical properties of surface-charged polymethylmethacrylate (PMMA)-based terpolymer and composite terpolymer core-silica shell particles in air and water media. The composite particles were achieved with two different approaches: using a silane coupling agent (composite A) or attractive electrostatic interactions (composite B) between the core and the shell. Young's moduli (E) of 4.3+/-0.7, 11.1+/-1.7, and 8.4+/-1.7 GPa were measured in air for the PMMA-based terpolymer, composite A, and composite B, respectively. In water, E decreases to 1.6+/-0.2 GPa for the terpolymer; it shows a slight decrease to 8.0+/-1.2 GPa for composite A, while it decreases to 2.9+/-0.6 GPa for composite B. This trend is explained by considering a 50% swelling of the polymer in water confirmed by dynamic light scattering. Close agreement is found between the absolute values of elastic moduli determined by nanoindentation and known values for the corresponding bulk materials. The thickness of the silica coating affects the mechanical properties of composite A. In the case of composite B, because the silica shell consists of separate particles free to move in the longitudinal direction that do not individually deform when the entire composite deforms, the elastic properties of the composites are determined exclusively by the properties of the polymer core. These results provide a basis for tailoring the mechanical properties of polymer and composite particles in air and in solution, essential in the design of next-generation abrasive schemes for several technological applications.

  10. Single Molecule Study on Polymer-Nanoparticle Interactions: The Particle Shape Matters.

    Science.gov (United States)

    Li, Zhandong; Zhang, Bin; Song, Yu; Xue, Yurui; Wu, Lixin; Zhang, Wenke

    2017-08-08

    The study on the nanoparticle-polymer interactions is very important for the design/preparation of high performance polymer nanocomposite. Here we present a method to quantify the polymer-particle interaction at single molecule level by using AFM-based single molecule force spectroscopy (SMFS). As a proof-of-concept study, we choose poly-l-lysine (PLL) as the polymer and several different types of polyoxometalates (POM) as the model particles to construct several different polymer nanocomposites and to reveal the binding mode and quantify the binding strength in these systems. Our results reveal that the shape of the nanoparticle and the binding geometry in the composite have significantly influenced the binding strength of the PLL/POM complexes. Our dynamic force spectroscopy studies indicate that the disk-like geometry facilitate the unbinding of PLL/AlMo 6 complexes in shearing mode, while the unzipping mode becomes dominate in spherical PLL-P 8 W 48 system. We have also systematically investigated the effects of charge numbers, particle size, and ionic strength on the binding strength and binding mode of PLL/POM, respectively. Our results show that electrostatic interactions dominate the stability of PLL/POM complexes. These findings provide a way for tuning the mechanical properties of polyelectrolyte-nanoparticle composites.

  11. Barrier hopping, viscous flow, and kinetic gelation in particle-polymer suspensions.

    Science.gov (United States)

    Chen, Y-L; Kobelev, V; Schweizer, K S

    2005-04-01

    The naive mode coupling-polymer reference interaction site model (MCT-PRISM) theory of gelation and elasticity of suspensions of hard sphere colloids or nanoparticles mixed with nonadsorbing polymers has been extended to treat the emergence of barriers, activated transport, and viscous flow. The barrier makes the dominant contribution to the single particle relaxation time and shear viscosity, and is a rich function of the depletion attraction strength via the polymer concentration, polymer-particle size asymmetry ratio, and particle volume fraction. The dependences of the barrier on these three system parameters can be accurately collapsed onto a single scaling variable, and the resultant master curve is well described by a power law. Nearly universal master curves are also constructed for the hopping or alpha relaxation time for system conditions not too close to the ideal MCT transition. Based on the calculated barrier hopping time, a theory for kinetic gel boundaries is proposed. The form and dependence on system parameters of the kinetic gel lines are qualitatively the same as obtained from prior ideal MCT-PRISM studies. The possible relevance of our results to the phenomenon of gravity-driven gel collapse is studied. The general approach can be extended to treat nonlinear viscoelasticity and rheology of polymer-colloid suspensions and gels.

  12. Aggregation of amphiphilic polymers in the presence of adhesive small colloidal particles.

    Science.gov (United States)

    Baulin, Vladimir A; Johner, Albert; Avalos, Josep Bonet

    2010-11-07

    The interaction of amphiphilic polymers with small colloids, capable to reversibly stick onto the chains, is studied. Adhesive small colloids in solution are able to dynamically bind two polymer segments. This association leads to topological changes in the polymer network configurations, such as looping and cross-linking, although the reversible adhesion permits the colloid to slide along the chain backbone. Previous analyses only consider static topologies in the chain network. We show that the sliding degree of freedom ensures the dominance of small loops, over other structures, giving rise to a new perspective in the analysis of the problem. The results are applied to the analysis of the equilibrium between colloidal particles and star polymers, as well as to block copolymer micelles. The results are relevant for the reversible adsorption of silica particles onto hydrophilic polymers, used in the process of formation of mesoporous materials of the type SBA or MCM, cross-linked cyclodextrin molecules threading on the polymers and forming the structures known as polyrotaxanes. Adhesion of colloids on the corona of the latter induce micellization and growth of larger micelles as the number of colloids increase, in agreement with experimental data.

  13. Fabrication of zeolite/polymer multilayer composite membranes for carbon dioxide capture: Deposition of zeolite particles on polymer supports.

    Science.gov (United States)

    Ramasubramanian, Kartik; Severance, Michael A; Dutta, Prabir K; Ho, W S Winston

    2015-08-15

    Membranes, due to their smaller footprint and potentially lower energy consumption than the amine process, offer a promising route for post-combustion CO2 capture. Zeolite Y based inorganic selective layers offer a favorable combination of CO2 permeance and CO2/N2 selectivity, membrane properties crucial to the economics. For economic viability on large scale, we propose to use flexible and scalable polymer supports for inorganic selective layers. The work described in this paper developed a detailed protocol for depositing thin zeolite Y seed layers on polymer supports, the first step in the synthesis of a polycrystalline zeolite Y membrane. We also studied the effects of support surface morphology (pore size and surface porosity) on the quality of deposition and identified favorable supports for the deposition. Two different zeolite Y particles with nominal sizes of 200 nm and 40 nm were investigated. To obtain a complete coverage of zeolite particles on the support surface with minimum defects and in a reproducible manner, a vacuum-assisted dip-coating technique was developed. Images obtained using both digital camera and optical microscope showed the presence of color patterns on the deposited surface which suggested that the coverage was complete. Electron microscopy revealed that the particle packing was dense with some drying cracks. Layer thickness with the larger zeolite Y particles was close to 1 μm while that with the smaller particles was reduced to less than 0.5 μm. In order to reduce drying cracks for layers with smaller zeolite Y particles, thickness was reduced by lowering the dispersion concentration. Transport measurement was used as an additional technique to characterize these layers. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Polypyrrole-palladium nanocomposite coating of micrometer-sized polymer particles toward a recyclable catalyst.

    Science.gov (United States)

    Fujii, Syuji; Matsuzawa, Soichiro; Hamasaki, Hiroyuki; Nakamura, Yoshinobu; Bouleghlimat, Azzedine; Buurma, Niklaas J

    2012-02-07

    A range of near-monodisperse, multimicrometer-sized polymer particles has been coated with ultrathin overlayers of polypyrrole-palladium (PPy-Pd) nanocomposite by chemical oxidative polymerization of pyrrole using PdCl(2) as an oxidant in aqueous media. Good control over the targeted PPy-Pd nanocomposite loading is achieved for 5.2 μm diameter polystyrene (PS) particles, and PS particles of up to 84 μm diameter can also be efficiently coated with the PPy-Pd nanocomposite. The seed polymer particles and resulting composite particles were extensively characterized with respect to particle size and size distribution, morphology, surface/bulk chemical compositions, and conductivity. Laser diffraction studies of dilute aqueous suspensions indicate that the polymer particles disperse stably before and after nanocoating with the PPy-Pd nanocomposite. The Fourier transform infrared (FT-IR) spectrum of the PS particles coated with the PPy-Pd nanocomposite overlayer is dominated by the underlying particle, since this is the major component (>96% by mass). Thermogravimetric and elemental analysis indicated that PPy-Pd nanocomposite loadings were below 6 wt %. The conductivity of pressed pellets prepared with the nanocomposite-coated particles increased with a decrease of particle diameter because of higher PPy-Pd nanocomposite loading. "Flattened ball" morphologies were observed by scanning/transmission electron microscopy after extraction of the PS component from the composite particles, which confirmed a PS core and a PPy-Pd nanocomposite shell morphology. X-ray diffraction confirmed the production of elemental Pd and X-ray photoelectron spectroscopy studies indicated the existence of elemental Pd on the surface of the composite particles. Transmission electron microscopy confirmed that nanometer-sized Pd particles were distributed in the shell. Near-monodisperse poly(methyl methacrylate) particles with diameters ranging between 10 and 19 μm have been also successfully

  15. Prediction of elastic properties for polymer-particle nanocomposites exhibiting an interphase

    International Nuclear Information System (INIS)

    Deng Fei; Van Vliet, Krystyn J

    2011-01-01

    Particle-polymer nanocomposites often exhibit mechanical properties described poorly by micromechanical models that include only the particle and matrix phases. Existence of an interfacial region between the particle and matrix, or interphase, has been posited and indirectly demonstrated to account for this effect. Here, we present a straightforward analytical approach to estimate effective elastic properties of composites comprising particles encapsulated by an interphase of finite thickness and distinct elastic properties. This explicit solution can treat nanocomposites that comprise either physically isolated nanoparticles or agglomerates of such nanoparticles; the same framework can also treat physically isolated nanoparticle aggregates or agglomerates of such aggregates. We find that the predicted elastic moduli agree with experiments for three types of particle-polymer nanocomposites, and that the predicted interphase thickness and stiffness of carbon black-rubber nanocomposites are consistent with measured values. Finally, we discuss the relative influence of the particle-polymer interphase thickness and stiffness to identify maximum possible changes in the macroscale elastic properties of such materials.

  16. Submicron polymer particles containing fluorescent semiconductor nanocrystals CdSe/ZnS for bioassays.

    Science.gov (United States)

    Generalova, Alla N; Sizova, Svetlana V; Zdobnova, Tatiana A; Zarifullina, Margarita M; Artemyev, Michail V; Baranov, Alexander V; Oleinikov, Vladimir A; Zubov, Vitaly P; Deyev, Sergey M

    2011-02-01

    This study aimed to design a panel of uniform particulate biochemical reagents and to test them in specific bioassays. These reagents are polymer particles of different sizes doped with semiconductor nanocrystals and conjugated with either full-size antibodies or recombinant mini-antibodies (4D5 scFv fragment) designed by genetic engineering approaches. A panel of highly fluorescent polymer particles (150-800 nm) were formed by embedding CdSe/ZnS nanocrystals (quantum dots) into preformed polyacrolein and poly(acrolein-co-styrene) particles. Morphology, content and fluorescence characteristics of the prepared materials were studied by laser correlation spectroscopy, spectrophotometry, optical and fluorescent microscopy and fluorimetry. The obtained fluorescent particles sensitized by anti-Yersinia pestis antibodies were used for rapid agglutination glass test suitable for screening analysis of Y. pestis antigen and for microtiter particle agglutination, which, owing to its speed and simplicity, is very beneficial for diagnostic detection of Y. pestis antigen. Recombinant 4D5 scFv antibodies designed and conjugated with polymer particles containing quantum dots provide multipoint highly specific binding with cancer marker HER2/neu on the surface of SKOV-3 cell.

  17. Nano-Particle Enhanced Polymer Materials for Space Flight Applications

    Science.gov (United States)

    Criss, Jim M., Jr.; Powell, William D.; Connell, John W.; Stallworth-Bordain, Yemaya; Brown, Tracy R.; Mintz, Eric A.; Schlea, Michelle R.; Shofne, Meisha L.

    2009-01-01

    Recent advances in materials technology both in polymer chemistry and nano-materials warrant development of enhanced structures for space flight applications. This work aims to develop spacecraft structures based on polymer matrix composites (PMCs) that utilize these advancements.. Multi-wall carbon nano-tubes (MWCNTs) are expected ·to increase mechanical performance, lower coefficient of thermal expansion (CTE), increase electrical conductivity (mitigate electrostatic charge), increase thermal conductivity, and reduce moisture absorption of the resultant space structures. In this work, blends of MWCNTs with PETI-330 were prepared and characterized. The nano-reinforced resins were then resin transfer molded (RTM) into composite panels using M55J carbon fabric and compared to baseline panels fabricated from a cyanate ester (RS-3) or a polyimide (PETI-330) resin containing no MWCNTs. In addition, methods of pre-loading the fabric with the MWCNTs were also investigated. The effects of the MWCNTs on the resin processing properties and on the composite end-use properties were also determined.

  18. Prazosin-Conjugated Matrices Based on Biodegradable Polymers and α-Amino Acids--Synthesis, Characterization, and in Vitro Release Study.

    Science.gov (United States)

    Oledzka, Ewa; Sawicka, Anna; Sobczak, Marcin; Nalecz-Jawecki, Grzegorz; Skrzypczak, Agata; Kolodziejski, Waclaw

    2015-08-12

    Novel and promising macromolecular conjugates of the α1-adrenergic blocker prazosin were directly synthesized by covalent incorporation of the drug to matrices composed of biodegradable polymers and α-amino acids for the development of a polymeric implantable drug delivery carrier. The cyto- and genotoxicity of the synthesized matrices were evaluated using a bacterial luminescence test, protozoan assay, and Salmonella typhimurium TA1535. A new urethane bond was formed between the hydroxyl end-groups of the synthesized polymer matrices and an amine group of prazosin, using 1,1'-carbonyldiimidazole (CDI) as a coupling agent. The structure of the polymeric conjugates was characterized by various spectroscopy techniques. A study of hydrogen nuclear magnetic resonance ((1)H-NMR) and differential scanning calorimetry (DSC) thermodiagrams indicated that the presence of prazosin pendant groups in the macromolecule structures increased the polymer's rigidity alongside increasing glass transition temperature. It has been found that the kinetic release of prazosin from the obtained macromolecular conjugates, tested in vitro under different conditions, is strongly dependent on the physicochemical properties of polymeric matrices. Furthermore, the presence of a urethane bond in the macromolecular conjugates allowed for obtaining a relatively controlled release profile of the drug. The obtained results confirm that the pharmacokinetics of prazosin might be improved through the synthesis of polymeric conjugates containing biomedical polymers and α-amino acids in the macromolecule.

  19. Coordination polymer network meso-particles: Thermodynamics and kinetics

    International Nuclear Information System (INIS)

    Sievers, Torsten K.; Demars, Thomas; Bonnefond, Florent; Genre, Caroline; Meyer, Daniel; Podor, Renaud

    2012-01-01

    Metal ion induced self assembly of dihydroxybenzoquinone and Neodymium in water yields within seconds a red solid precipitate, which is according to x-ray structure analysis a crystalline metal organic framework (MOF). However, scanning electron microscopy (SEM) and small angle x-ray scattering reveal that the precipitate is composed of micrometer sized particles, which themselves are composed of nanoparticles. Notably, these particles exhibit a judicious variety of shapes, which can be addressed individually by choosing the appropriate assembly condition. Importantly, some of these shapes, e.g. cylinder particles, are indicative for an assembly kinetics that is not driven by crystallinity but by a balance of inter nanoparticle and nanoparticle-solvent (water) interactions. We conducted an elaborate SEM study, during which we adjusted the water vapor pressure over a wide pressure range. Repeating this measurement at different temperatures, we were able to identify the transient pressures at which the particles begin to change size and calculated solvent-nanoparticle interaction energy. (authors)

  20. A novel bio-degradable polymer stabilized Ag/TiO2 nanocomposites and their catalytic activity on reduction of methylene blue under natural sun light.

    Science.gov (United States)

    Geetha, D; Kavitha, S; Ramesh, P S

    2015-11-01

    In the present work we defined a novel method of TiO2 doped silver nanocomposite synthesis and stabilization using bio-degradable polymers viz., chitosan (Cts) and polyethylene glycol (PEG). These polymers are used as reducing agents. The instant formation of AgNPs was analyzed by visual observation and UV-visible spectrophotometer. TiO2 nanoparticles doped at different concentrations viz., 0.03, 0.06 and 0.09mM on PEG/Cts stabilized silver (0.04wt%) were successfully synthesized. This study presents a simple route for the in situ synthesis of both metal and polymer confined within the nanomaterial, producing ternary hybrid inorganic-organic nanomaterials. The results reveal that they have higher photocatalytic efficiencies under natural sun light. The synthesized TiO2 doped Ag nanocomposites (NCs) were characterized by SEM/EDS, TEM, XRD, FTIR and DLS with zeta potential. The stability of Ag/TiO2 nanocomposite is due to the high negative values of zeta potential and capping of constituents present in the biodegradable polymer which is evident from zeta potential and FT-IR studies. The XRD and EDS pattern of synthesized Ag/TiO2 NCs showed their crystalline structure, with face centered cubic geometry oriented in (111) plane. AFM and DLS studies revealed that the diameter of stable Ag/TiO2 NCs was approximately 35nm. Moreover the catalytic activity of synthesize Ag/TiO2 NCs in the reduction of methylene blue was studied by UV-visible spectrophotometer. The synthesized Ag/TiO2 NCs are observed to have a good catalytic activity on the reduction of methylene blue by bio-degradable which is confirmed by the decrease in absorbance maximum value of methylene blue with respect to time using UV-vis spectrophotometer. The significant enhancement in the photocatalytic activity of Ag/TiO2 nanocomposites under sun light irradiation can be ascribed to the effect of noble metal Ag by acting as electron traps in TiO2 band gap. Copyright © 2015. Published by Elsevier Inc.

  1. Quantitative structure-activity relationships for green algae growth inhibition by polymer particles.

    NARCIS (Netherlands)

    Nolte, Tom M; Peijnenburg, Willie J G M; Hendriks, A Jan; van de Meent, Dik

    After use and disposal of chemical products, many types of polymer particles end up in the aquatic environment with potential toxic effects to primary producers like green algae. In this study, we have developed Quantitative Structure-Activity Relationships (QSARs) for a set of highly structural

  2. Molecular dynamics simulations of the embedding of a nano-particle into a polymer film

    International Nuclear Information System (INIS)

    Ochoa, J G Diaz; Binder, K; Paul, W

    2006-01-01

    In this work we report on molecular dynamics simulations of the embedding process of a nano-particle into a polymeric film as a function of temperature. This process has been employed experimentally in recent years to test for a shift of the glass transition of a material due to the confined film geometry and to test for the existence of a liquid-like layer on top of a glassy polymer film. The embedding process is governed thermodynamically by the prewetting properties of the polymer on the nano-particle. We show that the dynamics of the process depends on the Brownian motion characteristics of the nano-particle in and on the polymer film. It displays large sample to sample variations, suggesting that it is an activated process. On the timescales of the simulation an embedding of the nano-particle is only observed for temperatures above the bulk glass transition temperature of the polymer, agreeing with experimental observations on noble metal clusters of comparable size

  3. Nanocomposite coatings of Ti/C:H plasma polymer particles providing a surface with variable nanoroughness

    Czech Academy of Sciences Publication Activity Database

    Solař, P.; Kylián, O.; Polonskyi, O.; Artemenko, A.; Arzhakov, D.; Drábik, M.; Slavínská, D.; Vandrovcová, Marta; Bačáková, Lucie; Biederman, H.

    2012-01-01

    Roč. 206, č. 21 (2012), s. 4335-4342 ISSN 0257-8972 R&D Projects: GA AV ČR(CZ) KAN101120701 Institutional research plan: CEZ:AV0Z50110509 Keywords : plasma polymer particles * composite film * cell adhesion Subject RIV: EI - Biotechnology ; Bionics Impact factor: 1.941, year: 2012

  4. Failure-mode transition in transient polymer networks with particle-based simulations

    NARCIS (Netherlands)

    Sprakel, J.H.B.; Spruijt, E.; Padding, J.T.; Briels, W.J.

    2009-01-01

    Transient polymer networks are known to undergo a wide variety of viscoelastic flow instabilities. In this paper we investigate two of these flow failure modes: shear banding and melt fracture. Using particle-based simulations we reveal a transition from gradient banding to fracture in transient

  5. Molecular and structural properties of polymer composites filled with activated charcoal particles

    Science.gov (United States)

    Tahir, Dahlang; Liong, Syarifuddin; Bakri, Fahrul

    2016-03-01

    We have studied the molecular properties, structural properties, and chemical composition of composites by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy, and X-ray fluorescence (XRF) spectroscopy, respectively. FTIR spectra shows absorption band of hydroxyl group (-OH), methyl group (-CH3) and aromatic group (C-C). The absorption band for aromatic group (C-C) shows the formation of carbonaceous in composites. XRF shows chemical composition of composites, which the main chemicals are SO3, Cl, and ZnO. The loss on ignition value (LOI) of activated charcoal indicates high carbonaceous matter. The crystallite size for diffraction pattern from hydrogel polymer is about 17 nm and for activated charcoal are about 19 nm. The crystallite size of the polymer is lower than that of activated charcoal, which make possible of the particle from filler in contact with each other to form continuous conducting polymer through polymer matrix.

  6. Molecular and structural properties of polymer composites filled with activated charcoal particles

    Energy Technology Data Exchange (ETDEWEB)

    Tahir, Dahlang, E-mail: dtahir@fmipa.unhas.ac.id; Bakri, Fahrul [Department of Physics, Hasanuddin University, Makassar 90245 Indonesia (Indonesia); Liong, Syarifuddin [Department of Chemistry, Hasanuddin University, Makassar 90245 Indonesia (Indonesia)

    2016-03-11

    We have studied the molecular properties, structural properties, and chemical composition of composites by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) spectroscopy, and X-ray fluorescence (XRF) spectroscopy, respectively. FTIR spectra shows absorption band of hydroxyl group (-OH), methyl group (-CH{sub 3}) and aromatic group (C-C). The absorption band for aromatic group (C-C) shows the formation of carbonaceous in composites. XRF shows chemical composition of composites, which the main chemicals are SO{sub 3}, Cl, and ZnO. The loss on ignition value (LOI) of activated charcoal indicates high carbonaceous matter. The crystallite size for diffraction pattern from hydrogel polymer is about 17 nm and for activated charcoal are about 19 nm. The crystallite size of the polymer is lower than that of activated charcoal, which make possible of the particle from filler in contact with each other to form continuous conducting polymer through polymer matrix.

  7. Colloidal polymer particles as catalyst carriers and phase transfer agents in multiphasic hydroformylation reactions.

    Science.gov (United States)

    Peral, D; Stehl, D; Bibouche, B; Yu, H; Mardoukh, J; Schomäcker, R; Klitzing, R von; Vogt, D

    2018-03-01

    Colloidal particles have been used to covalently bind ligands for the heterogenization of homogeneous catalysts. The replacement of the covalent bonds by electrostatic interactions between particles and the catalyst could preserve the selectivity of a truly homogeneous catalytic process. Functionalized polymer particles with trimethylammonium moieties, dispersed in water, with a hydrophobic core and a hydrophilic shell have been synthesized by emulsion polymerization and have been thoroughly characterized. The ability of the particles with different monomer compositions to act as catalyst carriers has been studied. Finally, the colloidal dispersions have been applied as phase transfer agents in the multiphasic rhodium-catalyzed hydroformylation of 1-octene. The hydrodynamic radius of the particles has been shown to be around 100 nm, and a core-shell structure could be observed by atomic force microscopy. The polymer particles were proven to act as carriers for the water-soluble hydroformylation catalyst, due to electrostatic interaction between the functionalized particles bearing ammonium groups and the sulfonated ligands of the catalyst. The particles were stable under the hydroformylation conditions and the aqueous catalyst phase could be recycled three times. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Contribution to the study of particle resuspension kinetics during thermal degradation of polymers.

    Science.gov (United States)

    Ouf, F-X; Delcour, S; Azema, N; Coppalle, A; Ferry, L; Gensdarmes, F; Lopez-Cuesta, J-M; Niang, A; Pontreau, S; Yon, J

    2013-04-15

    Experimental results are reported on the resuspension of particles deposited on polymer samples representative of glove boxes used in the nuclear industry, under thermal degradation. A parametric study was carried out on the effects of heat flux, air flow rate, fuel type and particle size distribution. Small-scale experiments were conducted on 10 cm × 10 cm PolyMethyl MethAcrylate (PMMA) and PolyCarbonate (PC) samples covered with aluminium oxide particles with physical geometric diameters of 0.7 and 3.6 μm. It was observed for both polymer (fuel) samples that heat flux has no effect on the airborne release fraction (ARF), whereas particle size is a significant parameter. In the case of the PMMA sample, ARF values for 0.7 and 3.6 μm diameter particles range from 12.2% (± 6.2%) to 2.1% (± 0.6%), respectively, whereas the respective values for the PC sample range from 3.2% (± 0.8%) to 6.9% (± 3.9%). As the particle diameter increases, a significant decrease in particle release is observed for the PMMA sample, whereas an increase is observed for the PC sample. Furthermore, a peak airborne release rate is observed during the first instants of PMMA exposure to thermal stress. An empirical relationship has been proposed between the duration of this peak release and the external heat flux. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Particle synthesis, characterization, and properties of filled polymer systems

    Science.gov (United States)

    Kohls, Douglas J.

    This dissertation presents results on the reinforcement of an elastomer system using different types of fillers and comparing the resulting mechanical properties of compounds made with these fillers. The analytic approach uses two classical models with which fillers are thought to reinforce elastomers. The first mechanism being based on filler structure while the second involves the interaction of the filler with an elastomer. Two new types of fillers are investigated: a fumed silica-carbon composite and a layered silicate. These fillers are compounded into elastomers using formulations that are standard in the tire industry for tire tread compounds. This work builds off of previous studies that use techniques such as microscopy and gas adsorption to characterize filler structure by adding the use of small-angle x-ray scattering to characterize fillers based on three structural levels. Classical rubber elasticity principles with recent fractal model analysis are used to describe how the structural levels of the fillers relate to elastomer reinforcement. Analysis of the SAXS data gives information about the size of the primary particle and of the aggregate formed by these primary particles. It is found, through analyzing the SAXS data, that the ratio of these two structural sizes gives the degree of aggregation or the number of particles in an aggregate. The measurement and analysis of the degree of aggregation and how it correlates with measured mechanical properties of compounds is presented in this dissertation. The results from the USAXS and the mechanical testing of elastomers showed that the degree of aggregation, z, helps to identify what is a 'reinforcing' filler. Higher degree of aggregation correlated with better mechanical properties. While other studies have shown the effects of surface modifications, filler concentration, and surface area, the studies in this dissertation conclude that the degree of aggregation is an important parameter that can predict

  10. Characterization of deoxyribonuclease I immobilized on magnetic hydrophilic polymer particles

    Czech Academy of Sciences Publication Activity Database

    Rittich, B.; Španová, A.; Ohlashennyy, Y.; Lenfeld, Jiří; Rudolf, I.; Horák, Daniel; Beneš, Milan J.

    2002-01-01

    Roč. 774, č. 1 (2002), s. 25-31 ISSN 0378-4347. [International Symposium on Separations in the Biosciences /2./. Prague, 17.09.2001-20.09.2001] R&D Projects: GA ČR GA203/98/1231; GA ČR GA203/00/1339 Institutional research plan: CEZ:AV0Z4050913 Keywords : magnetic bead cellulose particles * magnetic poly(HEMA-co-EDMA * deoxyribonuclease I Subject RIV: CC - Organic Chemistry Impact factor: 1.913, year: 2002

  11. Biodegradable polymer nanocomposites based on natural nanotubes: effect of magnetically modified halloysite on the behaviour of polycaprolactone

    Czech Academy of Sciences Publication Activity Database

    Khunová, V.; Šafařík, Ivo; Škrátek, M.; Kelnar, Ivan; Tomanová, K.

    2016-01-01

    Roč. 51, č. 3 (2016), s. 435-444 ISSN 0009-8558 R&D Projects: GA ČR(CZ) GA13-15255S Institutional support: RVO:60077344 ; RVO:61389013 Keywords : magnetically modified HNTs * biodegradable poly mer nanocomposites * poly caprolactone Subject RIV: CD - Macromolecular Chemistry; JI - Composite Materials (UMCH-V) Impact factor: 1.052, year: 2016

  12. Biodegradable porous sheet-like scaffolds for soft-tissue engineering using a combined particulate leaching of salt particles and magnetic sugar particles.

    Science.gov (United States)

    Hu, Chengzhi; Tercero, Carlos; Ikeda, Seiichi; Nakajima, Masahiro; Tajima, Hirotaka; Shen, Yajing; Fukuda, Toshio; Arai, Fumihito

    2013-07-01

    Scaffolds serving as artificial extracellular matrixes (ECMs) play a pivotal role in the process of tissue regeneration by providing optimal cellular environments for penetration, ingrowth, and vascularization. Stacks of sheet-like scaffold can be engineered to become artificial ECMs, suggesting a great potential for achieving complex 3-D tissue regeneration to support cell survival and growth. In this study, we proposed and investigated a combined particulate leaching of magnetic sugar particles (MSPs) and salt particles for the development of a sheet-like scaffold. MSPs were fabricated by encapsulating NdFeB particles inside sugar spheres and were controlled using magnetic fields as a porogen to control pore size, pore structure and pore density while fabricating the scaffold. We studied the influence of the strength of the magnetic fields in controlling the coating thickness of the unmagnetized MSPs during the fabrication of the sheet-like scaffolds. The experimental relationship between magnetic flux density and the thickness of the MSP layer was illustrated. Furthermore, we investigated the infiltration capacity of different concentrations of poly(L-lactide-co-ɛ-caprolactone) (PLCL) as a scaffold material on MSP clusters. Following polymer casting and removal of the sugar template, spherical pores were generated inside the scaffolds. Cultivation of NIH/3T3 fibroblasts on the fabricated scaffold proves that the proposed method can be applied in the cell sheet fabrication. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  13. Removal of toxic uranium from synthetic nuclear power reactor effluents using uranyl ion imprinted polymer particles.

    Science.gov (United States)

    Preetha, Chandrika Ravindran; Gladis, Joseph Mary; Rao, Talasila Prasada; Venkateswaran, Gopala

    2006-05-01

    Major quantities of uranium find use as nuclear fuel in nuclear power reactors. In view of the extreme toxicity of uranium and consequent stringent limits fixed by WHO and various national governments, it is essential to remove uranium from nuclear power reactor effluents before discharge into environment. Ion imprinted polymer (IIP) materials have traditionally been used for the recovery of uranium from dilute aqueous solutions prior to detection or from seawater. We now describe the use of IIP materials for selective removal of uranium from a typical synthetic nuclear power reactor effluent. The IIP materials were prepared for uranyl ion (imprint ion) by forming binary salicylaldoxime (SALO) or 4-vinylpyridine (VP) or ternary SALO-VP complexes in 2-methoxyethanol (porogen) and copolymerizing in the presence of styrene (monomer), divinylbenzene (cross-linking monomer), and 2,2'-azobisisobutyronitrile (initiator). The resulting materials were then ground and sieved to obtain unleached polymer particles. Leached IIP particles were obtained by leaching the imprint ions with 6.0 M HCl. Control polymer particles were also prepared analogously without the imprint ion. The IIP particles obtained with ternary complex alone gave quantitative removal of uranyl ion in the pH range 3.5-5.0 with as low as 0.08 g. The retention capacity of uranyl IIP particles was found to be 98.50 mg/g of polymer. The present study successfully demonstrates the feasibility of removing uranyl ions selectively in the range 5 microg - 300 mg present in 500 mL of synthetic nuclear power reactor effluent containing a host of other inorganic species.

  14. Molecular identification of polymers and anthropogenic particles extracted from oceanic water and fish stomach - A Raman micro-spectroscopy study.

    Science.gov (United States)

    Ghosal, Sutapa; Chen, Michael; Wagner, Jeff; Wang, Zhong-Min; Wall, Stephen

    2018-02-01

    Pacific Ocean trawl samples, stomach contents of laboratory-raised fish as well as fish from the subtropical gyres were analyzed by Raman micro-spectroscopy (RMS) to identify polymer residues and any detectable persistent organic pollutants (POP). The goal was to access specific molecular information at the individual particle level in order to identify polymer debris in the natural environment. The identification process was aided by a laboratory generated automated fluorescence removal algorithm. Pacific Ocean trawl samples of plastic debris associated with fish collection sites were analyzed to determine the types of polymers commonly present. Subsequently, stomach contents of fish from these locations were analyzed for ingested polymer debris. Extraction of polymer debris from fish stomach using KOH versus ultrapure water were evaluated to determine the optimal method of extraction. Pulsed ultrasonic extraction in ultrapure water was determined to be the method of choice for extraction with minimal chemical intrusion. The Pacific Ocean trawl samples yielded primarily polyethylene (PE) and polypropylene (PP) particles >1 mm, PE being the most prevalent type. Additional microplastic residues (1 mm - 10 μm) extracted by filtration, included a polystyrene (PS) particle in addition to PE and PP. Flame retardant, deca-BDE was tentatively identified on some of the PP trawl particles. Polymer residues were also extracted from the stomachs of Atlantic and Pacific Ocean fish. Two types of polymer related debris were identified in the Atlantic Ocean fish: (1) polymer fragments and (2) fragments with combined polymer and fatty acid signatures. In terms of polymer fragments, only PE and PP were detected in the fish stomachs from both locations. A variety of particles were extracted from oceanic fish as potential plastic pieces based on optical examination. However, subsequent RMS examination identified them as various non-plastic fragments, highlighting the importance

  15. 2-year outcome after biodegradable polymer sirolimus- and biolimus- eluting coronary stents.From the randomized SORT OUT VII trial

    DEFF Research Database (Denmark)

    Jensen, Lisette Okkels; Maeng, Michael; Raungaard, Bent

    2018-01-01

    AIMS: The SORT OUT VII trial compared the thin-strut cobalt-chromium sirolimus-eluting Orsiro stent with a slow polymer degradation and the thicker-strut stainless steel biolimus-eluting Nobori stent with a moderate-term polymer degradation in an all-comer patient population. METHODS AND RESULTS...

  16. Biodegradable polymer drug-eluting stents versus second-generation drug-eluting stents for patients with coronary artery disease: an update meta-analysis.

    Science.gov (United States)

    Wang, Yanyu; Dong, Pingshuan; Li, Ling; Li, Xiaoling; Wang, Hongyun; Yang, Xuming; Wang, Shaoxin; Li, Zhuanzhen; Shang, Xiyan

    2014-08-01

    Permanent polymer drug-eluting stents (DES) are associated with a higher risk of late and very late stent thrombosis (ST); biodegradable polymer drug-eluting stents (BP-DES) were designed to reduce these risks. However, their benefits are not completely clear. We undertook a meta-analysis of randomized studies identified in systematic searches of MEDLINE, EMBASE, and the Cochrane Database. Eligible studies were those that compared BP-DES with second-generation permanent polymer DES in patients undergoing percutaneous coronary intervention. Five studies (8,740 patients) with a mean follow-up of 19.2 months were included. Overall, BP-DES were associated with a broadly equivalent risk of definite and probable ST (odds ratio [OR], 1.07; 95 % confidence interval [CI], 0.67 to 1.71; P = 0.76; I (2) = 5.0 %), target vessel revascularization (OR, 1.04; 95 % CI, 0.87 to 1.24; P = 0.68; I (2) = 38.0 %), all-cause mortality (OR, 1.10; 95 % CI, 0.87 to 1.41; P = 0.42; I (2) = 0.0 %), and major adverse cardiac events (OR, 1.03; 95 % CI, 0.88 to 1.20; P = 0.74; I (2) = 0.0 %) when compared with second-generation DES. However, BP-DES significantly decreased in-stent late luminal loss (standard mean difference [SMD], -0.01; 95 % CI, -0.12 to 0.11; P = 0.93; I (2) = 0.0 %) and in-segment late luminal loss (SMD, -0.06; 95 % CI, -0.17 to 0.05; P = 0.27; I (2) = 0.0 %) compared with second-generation DES. Compared with second-generation permanent polymer DES, biodegradable stents appear to have equivalent short- to medium-term clinical benefits, and it remains unclear whether they reduce the incidence of very late ST.

  17. Polymer blend particles with defined compositions for targeting antigen to both class I and II antigen presentation pathways.

    Science.gov (United States)

    Tran, Kenny K; Zhan, Xi; Shen, Hong

    2014-05-01

    Defense against many persistent and difficult-to-treat diseases requires a combination of humoral, CD4(+) , and CD8(+) T-cell responses, which necessitates targeting antigens to both class I and II antigen presentation pathways. In this study, polymer blend particles are developed by mixing two functionally unique polymers, poly(lactide-co-glycolide) (PLGA) and a pH-responsive polymer, poly(dimethylaminoethyl methacrylate-co-propylacrylic acid-co-butyl methacrylate) (DMAEMA-co-PAA-co-BMA). Polymer blend particles are shown to enable the delivery of antigens into both class I and II antigen presentation pathways in vitro. Increasing the ratio of the pH-responsive polymer in blend particles increases the degree of class I antigen presentation, while maintaining high levels of class II antigen presentation. In a mouse model, it is demonstrated that a significantly higher and sustained level of CD4(+) and CD8(+) T-cell responses, and comparable antibody responses, are elicited with polymer blend particles than PLGA particles and a conventional vaccine, Alum. The polymer blend particles offer a potential vaccine delivery platform to generate a combination of humoral and cell-mediated immune responses that insure robust and long-lasting immunity against many infectious diseases and cancers. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Microbial community structure and biodegradation activity of particle-associated bacteria in a coal tar contaminated creek

    Energy Technology Data Exchange (ETDEWEB)

    Jennifer M. DeBruyn; Gary S. Sayler [University of Tennessee, Knoxville, TN (United States). Center for Environmental Biotechnology and Department of Microbiology

    2009-05-01

    The Chattanooga Creek Superfund site (Chattanooga, TN) is one of the most polluted waterways in the southeastern U.S. with high polycyclic aromatic hydrocarbon (PAH) concentrations in the sediments. PAHs associate with suspended solids in the water column, and may be redeposited onto the floodplain. These suspended particles represent an interesting but understudied environment for PAH-degrading microbial communities. This study tested the hypotheses that particle-associated bacterial (PAB) communities have genotypic potential (PAH-dioxygenase genes) and activity (naphthalene and pyrene mineralization), and can contribute to natural attenuation of PAHs in Chattanooga Creek. Upstream of the Superfund site, mineralization ranged from 0.2 to 2.0% of added {sup 14}C-naphthalene and 0 to 0.1% {sup 14}C-pyrene (after 40 h), with first order biodegradation rate constants (k{sub 1}) ranging from 1.09 to 9.18 x 10{sup -5} h{sup -1} and 0 to 1.13 x 10{sup -6} h{sup -1}, respectively. Mineralization was significantly greater in PAB communities within the contaminated zone, with 11.8 to 31.2% {sup 14}C-naphthalene (k{sup 1} 5.34 to 14.2 x 10-4 h{sup -1}) and 1.3 to 6.6% {sup 14}C-pyrene mineralized (k{sub 1} 2.89 to 15.0 x 10{sup -5} h{sup -1}). Abundances of nagAc (naphthalene dioxygenase) and nidA (pyrene dioxygenase) genes indicated that PAB communities harbored populations with genetic potential for both low- and high-molecular weight PAH degradation, and quantification of Mycobacterium 16S rDNA genes indicated that PAH-degrading mycobacteria are also prevalent in this environment. Phylogenetic comparisons (T-RFLPs) between PAB and sediments indicated these microbial communities were taxonomically distinct, but shared some functional similarities, namely PAH catabolic genotypes, mineralization capabilities, and community structuring along a contamination gradient. 38 refs., 4 figs., 2 tabs.

  19. Physical characterization and in silico modeling of inulin polymer conformation during vaccine adjuvant particle formation.

    Science.gov (United States)

    Barclay, Thomas G; Rajapaksha, Harinda; Thilagam, Alagu; Qian, Gujie; Ginic-Markovic, Milena; Cooper, Peter D; Gerson, Andrea; Petrovsky, Nikolai

    2016-06-05

    This study combined physical data from synchrotron SAXS, FTIR and microscopy with in-silico molecular structure predictions and mathematical modeling to examine inulin adjuvant particle formation and structure. The results show that inulin polymer chains adopt swollen random coil in solution. As precipitation occurs from solution, interactions between the glucose end group of one chain and a fructose group of an adjacent chain help drive organized assembly, initially forming inulin ribbons with helical organization of the chains orthogonal to the long-axis of the ribbon. Subsequent aggregation of the ribbons results in the layered semicrystalline particles previously shown to act as potent vaccine adjuvants. γ-Inulin adjuvant particles consist of crystalline layers 8.5 nm thick comprising helically organized inulin chains orthogonal to the plane of the layer. These crystalline layers alternate with amorphous layers 2.4 nm thick, to give overall particle crystallinity of 78%. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Trends in Polymer and Particle Characterization by Microfluidic Field-Flow Fractionation Methods: Science or Business?

    Czech Academy of Sciences Publication Activity Database

    Janča, Josef; Sobota, Jaroslav

    2014-01-01

    Roč. 19, 16 May (2014), s. 296-308 ISSN 1023-666X R&D Projects: GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : Asymmetrical flow FFF * Electrical FFF * Field-flow fractionation * Flow FFF * Microelectrical FFF * Microfluidic channels * Microthermal FFF * Miniaturization and resolution * Polymers and particles separation * Sedimentation FFF * Technical benefits of microchannels * Thermal FFF Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.264, year: 2014

  1. Advanced analysis of polymer emulsions: Particle size and particle size distribution by field-flow fractionation and dynamic light scattering.

    Science.gov (United States)

    Makan, Ashwell C; Spallek, Markus J; du Toit, Madeleine; Klein, Thorsten; Pasch, Harald

    2016-04-15

    Field flow fractionation (FFF) is an advanced fractionation technique for the analyses of very sensitive particles. In this study, different FFF techniques were used for the fractionation and analysis of polymer emulsions/latexes. As model systems, a pure acrylic emulsion and emulsions containing titanium dioxide were prepared and analyzed. An acrylic emulsion polymerization was conducted, continuously sampled from the reactor and subsequently analyzed to determine the particle size, radius of gyration in specific, of the latex particles throughout the polymerization reaction. Asymmetrical flow field-flow fractionation (AF4) and sedimentation field-flow fractionation (SdFFF), coupled to a multidetector system, multi-angle laser light scattering (MALLS), ultraviolet (UV) and refractive index (RI), respectively, were used to investigate the evolution of particle sizes and particle size distributions (PSDs) as the polymerization progressed. The obtained particle sizes were compared against batch-mode dynamic light scattering (DLS). Results indicated differences between AF4 and DLS results due to DLS taking hydration layers into account, whereas both AF4 and SdFFF were coupled to MALLS detection, hence not taking the hydration layer into account for size determination. SdFFF has additional separation capabilities with a much higher resolution compared to AF4. The calculated radii values were 5 nm larger for SdFFF measurements for each analyzed sample against the corresponding AF4 values. Additionally a low particle size shoulder was observed for SdFFF indicating bimodality in the reactor very early during the polymerization reaction. Furthermore, different emulsions were mixed with inorganic species used as additives in cosmetics and coatings such as TiO2. These complex mixtures of species were analyzed to investigate the retention and particle interaction behavior under different AF4 experimental conditions, such as the mobile phase. The AF4 system was coupled online

  2. Exploring Electronic Structure and Order in Polymers via Single-Particle Microresonator Spectroscopy.

    Science.gov (United States)

    Horak, Erik H; Rea, Morgan T; Heylman, Kevin D; Gelbwaser-Klimovsky, David; Saikin, Semion K; Thompson, Blaise J; Kohler, Daniel D; Knapper, Kassandra A; Wei, Wei; Pan, Feng; Gopalan, Padma; Wright, John C; Aspuru-Guzik, Alán; Goldsmith, Randall H

    2018-02-08

    PSS, a transparent electrically conductive polymer, finds widespread use in electronic devices. While empirical efforts have increased conductivity, a detailed understanding of the coupled electronic and morphological landscapes in PEDOT:PSS has lagged due to substantial structural heterogeneity on multiple length-scales. We use an optical microresonator-based absorption spectrometer to perform single-particle measurements, providing a bottom-up examination of electronic structure and morphology ranging from single PEDOT:PSS polymers to nascent films. Using single-particle spectroscopy with complementary theoretical calculations and ultrafast spectroscopy, we demonstrate that PEDOT:PSS displays bulk-like optical response even in single polymers. We find highly ordered PEDOT assemblies with long-range ordering mediated by the insulating PSS matrix and reveal a preferential surface orientation of PEDOT nanocrystallites absent in bulk films with implications for interfacial electronic communication. Our single-particle perspective provides a unique window into the microscopic structure and electronic properties of PEDOT:PSS.

  3. Biodegradable modified Phba systems

    International Nuclear Information System (INIS)

    Aniscenko, L.; Dzenis, M.; Erkske, D.; Tupureina, V.; Savenkova, L.; Muizniece - Braslava, S.

    2004-01-01

    Compositions as well as production technology of ecologically sound biodegradable multicomponent polymer systems were developed. Our objective was to design some bio plastic based composites with required mechanical properties and biodegradability intended for use as biodegradable packaging. Significant characteristics required for food packaging such as barrier properties (water and oxygen permeability) and influence of γ-radiation on the structure and changes of main characteristics of some modified PHB matrices was evaluated. It was found that barrier properties were plasticizers chemical nature and sterilization with γ-radiation dependent and were comparable with corresponding values of typical polymeric packaging films. Low γ-radiation levels (25 kGy) can be recommended as an effective sterilization method of PHB based packaging materials. Purposely designed bio plastic packaging may provide an alternative to traditional synthetic packaging materials without reducing the comfort of the end-user due to specific qualities of PHB - biodegradability, Biocompatibility and hydrophobic nature

  4. Comparison of Vascular Responses Following New-Generation Biodegradable and Durable Polymer-Based Drug-Eluting Stent Implantation in an Atherosclerotic Rabbit Iliac Artery Model.

    Science.gov (United States)

    Nakazawa, Gaku; Torii, Sho; Ijichi, Takeshi; Nagamatsu, Hirofumi; Ohno, Yohei; Kurata, Fumi; Yoshikawa, Ayako; Nakano, Masataka; Shinozaki, Norihiko; Yoshimachi, Fuminobu; Ikari, Yuji

    2016-10-19

    Incomplete endothelialization is the primary substrate of late stent thrombosis; however, recent reports have revealed that abnormal vascular responses are also responsible for the occurrence of late stent failure. The aim of the current study was to assess vascular response following deployment of biodegradable polymer-based Synergy (Boston Scientific) and Nobori (Terumo) drug-eluting stents and the durable polymer-based Resolute Integrity stent (Medtronic) in an atherosclerotic rabbit iliac artery model. A total of 24 rabbits were fed an atherogenic diet, and then a balloon injury was used to induce atheroma formation. Synergy, Nobori, and Resolute Integrity stents were randomly implanted in iliac arteries. Animals were euthanized at 28 days for scanning electron microscopic evaluation and at 90 days for histological analysis. The percentage of uncovered strut area at 28 days was lowest with Synergy, followed by Resolute Integrity, and was significantly higher with Nobori stents (Synergy 1.1±2.2%, Resolute Integrity 2.0±3.9%, Nobori 4.6±3.0%; Pfastest stent strut neointimal coverage and the lowest incidence of neoatherosclerosis in the current animal model. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

  5. Statistical optimization of microencapsulation process for coating of magnesium particles with Viton polymer

    Energy Technology Data Exchange (ETDEWEB)

    Pourmortazavi, Seied Mahdi, E-mail: pourmortazavi@yahoo.com [Faculty of Material and Manufacturing Technologies, Malek Ashtar University of Technology, P.O. Box 16765-3454, Tehran (Iran, Islamic Republic of); Babaee, Saeed; Ashtiani, Fatemeh Shamsi [Faculty of Chemistry & Chemical Engineering, Malek Ashtar University of Technology, Tehran (Iran, Islamic Republic of)

    2015-09-15

    Graphical abstract: - Highlights: • Surface of magnesium particles was modified with Viton via solvent/non-solvent method. • FT-IR, SEM, EDX, Map analysis, and TG/DSC techniques were employed to characterize the coated particles. • Coating process factors were optimized by Taguchi robust design. • The importance of coating conditions on resistance of coated magnesium against oxidation was studied. - Abstract: The surface of magnesium particles was modified by coating with Viton as an energetic polymer using solvent/non-solvent technique. Taguchi robust method was utilized as a statistical experiment design to evaluate the role of coating process parameters. The coated magnesium particles were characterized by various techniques, i.e., Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and thermogravimetry (TG), and differential scanning calorimetry (DSC). The results showed that the coating of magnesium powder with the Viton leads to a higher resistance of metal against oxidation in the presence of air atmosphere. Meanwhile, tuning of the coating process parameters (i.e., percent of Viton, flow rate of non-solvent addition, and type of solvent) influences on the resistance of the metal particles against thermal oxidation. Coating of magnesium particles yields Viton coated particles with higher thermal stability (632 °C); in comparison with the pure magnesium powder, which commences oxidation in the presence of air atmosphere at a lower temperature of 260 °C.

  6. Can Platforms Affect the Safety and Efficacy of Drug-Eluting Stents in the Era of Biodegradable Polymers?: A Meta-Analysis of 34,850 Randomized Individuals.

    Science.gov (United States)

    Yan, Yun-Feng; Jiang, Long; Zhang, Ming-Duo; Li, Xin-He; Nie, Mao-Xiao; Feng, Ting-Ting; Zhao, Xin; Wang, Lu-Ya; Zhao, Quan-Ming

    2016-01-01

    In the era of bare metal stents (BMSs), alloys have been considered to be better materials for stent design than stainless steel. In the era of biodegradable polymer drug-eluting stents (BP-DESs), the safety and efficacy of BP-DESs with different metal platforms (stainless steel or alloys) have not yet been reported, although their polymers are eventually absorbed, and only the metal platforms remain in the body. This study sought to determine the clinical safety and efficacy of BP-DESs with different platforms compared with other stents (other DESs and BMSs). PubMed, Embase and Clinical Trials.gov were searched for randomized controlled trials (RCTs) that compared BP-DESs with other stents. After performing pooled analysis of BP-DESs and other stents, we performed a subgroup analysis using two classification methods: stent platform and follow-up time. The study characteristics, patient characteristics and clinical outcomes were abstracted. Forty RCTs (49 studies) comprising 34,850 patients were included. Biodegradable polymer stainless drug-eluting stents (BP-stainless DESs) were superior to the other stents [mainly stainless drug-eluting stents (DESs)] in terms of pooled definite/probable stent thrombosis (ST) (OR [95% CI] = 0.76[0.61-0.95], p = 0.02), long-term definite/probable ST (OR [95% CI] = 0.73[0.57-0.94], p = 0.01), very late definite/probable ST (OR [95% CI] = 0.56[0.33-0.93], p = 0.03) and long-term definite ST. BP-stainless DESs had lower rates of pooled, mid-term and long-term target vessel revascularization (TVR) and target lesion revascularization (TLR) than the other stainless DESs and BMSs. Furthermore, BP-stainless DESs were associated with lower rates of long-term death than other stainless DESs and lower rates of mid-term myocardial infarction than BMSs. However, only the mid-term and long-term TVR rates were superior in BP-alloy DESs compared with the other stents. Our results indirectly suggest that BP-stainless DESs may offer more benefits

  7. Can Platforms Affect the Safety and Efficacy of Drug-Eluting Stents in the Era of Biodegradable Polymers?: A Meta-Analysis of 34,850 Randomized Individuals.

    Directory of Open Access Journals (Sweden)

    Yun-Feng Yan

    Full Text Available In the era of bare metal stents (BMSs, alloys have been considered to be better materials for stent design than stainless steel. In the era of biodegradable polymer drug-eluting stents (BP-DESs, the safety and efficacy of BP-DESs with different metal platforms (stainless steel or alloys have not yet been reported, although their polymers are eventually absorbed, and only the metal platforms remain in the body. This study sought to determine the clinical safety and efficacy of BP-DESs with different platforms compared with other stents (other DESs and BMSs.PubMed, Embase and Clinical Trials.gov were searched for randomized controlled trials (RCTs that compared BP-DESs with other stents. After performing pooled analysis of BP-DESs and other stents, we performed a subgroup analysis using two classification methods: stent platform and follow-up time. The study characteristics, patient characteristics and clinical outcomes were abstracted.Forty RCTs (49 studies comprising 34,850 patients were included. Biodegradable polymer stainless drug-eluting stents (BP-stainless DESs were superior to the other stents [mainly stainless drug-eluting stents (DESs] in terms of pooled definite/probable stent thrombosis (ST (OR [95% CI] = 0.76[0.61-0.95], p = 0.02, long-term definite/probable ST (OR [95% CI] = 0.73[0.57-0.94], p = 0.01, very late definite/probable ST (OR [95% CI] = 0.56[0.33-0.93], p = 0.03 and long-term definite ST. BP-stainless DESs had lower rates of pooled, mid-term and long-term target vessel revascularization (TVR and target lesion revascularization (TLR than the other stainless DESs and BMSs. Furthermore, BP-stainless DESs were associated with lower rates of long-term death than other stainless DESs and lower rates of mid-term myocardial infarction than BMSs. However, only the mid-term and long-term TVR rates were superior in BP-alloy DESs compared with the other stents.Our results indirectly suggest that BP-stainless DESs may offer more

  8. Preclinical investigation for developing injectable fiducial markers using a mixture of BaSO{sub 4} and biodegradable polymer for proton therapy

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Sang Hee [Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul 135-710 (Korea, Republic of); Gil, Moon Soo; Lee, Doo Sung [Sungkyunkwan University School of Chemical Engineering, Suwon 440-746 (Korea, Republic of); Han, Youngyih, E-mail: youngyih@skku.edu, E-mail: Hee.ro.Park@samsung.com; Park, Hee Chul, E-mail: youngyih@skku.edu, E-mail: Hee.ro.Park@samsung.com; Yu, Jeong Il; Noh, Jae Myoung; Cho, Jun Sang; Ahn, Sung Hwan; Choi, Doo Ho [Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 135-710 (Korea, Republic of); Sohn, Jason W. [Department of Radiation Oncology, Case Medical Center, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106 (United States); Kim, Hye Yeong; Shin, Eun Hyuk [Department of Radiation Oncology, Samsung Medical Center, Seoul 135-710 (Korea, Republic of)

    2015-05-15

    Purpose: The aim of this study is to investigate the use of mixture of BaSO{sub 4} and biodegradable polymer as an injectable nonmetallic fiducial marker to reduce artifacts in x-ray images, decrease the absorbed dose distortion in proton therapy, and replace permanent metal markers. Methods: Two samples were made with 90 wt. % polymer phosphate buffer saline (PBS) and 10 wt. % BaSO{sub 4} (B1) or 20 wt. % BaSO{sub 4} (B2). Two animal models (mice and rats) were used. To test the injectability and in vivo gelation, a volume of 200 μl at a pH 5.8 were injected into the Sprague-Dawley rats. After sacrificing the rats over time, the authors checked the gel morphology. Detectability of the markers in the x-ray images was tested for two sizes (diameters of 1 and 2 mm) for B1 and B2. Four samples were injected into BALB/C mice. The polymer mixed with BaSO{sub 4} transform from SOL at 20 °C with a pH of 6.0 to GEL in the living body at 37 °C with a pH of 7.4, so the size of the fiducial marker could be controlled by adjusting the injected volume. The detectability of the BaSO{sub 4} marker was measured in x-ray images of cone beam CT (CBCT), on-board imager [anterior–posterior (AP), lateral], and fluoroscopy (AP, lateral) using a Novalis-TX (Varian Medical Systems, Palo Alto, CA) repeatedly over 4 months. The volume, HU, and artifacts for the markers were measured in the CBCT images. Artifacts were compared to those of gold marker by analyzing the HU distribution. The dose distortion in proton therapy was computed by using a Monte Carlo (MC) code. A cylindrical shaped marker (diameter: 1 or 2 mm, length: 3 mm) made of gold, stainless-steel [304], titanium, and 20 wt. % BaSO{sub 4} was positioned at the center of the spread-out Bragg peak (SOBP) in parallel or perpendicular to the beam entrance. The dose distortion was measured on the depth dose profile across the markers. Results: Transformation to GEL and the biodegradation were verified. All BaSO{sub 4} markers

  9. Effect of modified starch and nanoclay particles on biodegradability and mechanical properties of cross-linked poly lactic acid.

    Science.gov (United States)

    Shayan, M; Azizi, H; Ghasemi, I; Karrabi, M

    2015-06-25

    Mechanical properties and biodegradation of cross-linked poly(lactic acid) (PLA)/maleated thermoplastic starch (MTPS)/montmorillonite (MMT) nanocomposite were studied. Crosslinking was carried out by adding di-cumyl peroxide (DCP) in the presence of triallyl isocyanurate (TAIC) as coagent. At first, MTPS was prepared by grafting maleic anhydride (MA) to thermoplastic starch in internal mixer. Experimental design was performed by using Box-Behnken method at three variables: MTPS, nanoclay and TAIC at three levels. Results showed that increasing TAIC amount substantially increased the gel fraction, enhanced tensile strength, and caused a decrease in elongation at break. Biodegradation was prevented by increasing TAIC amount in nanocomposite. Increasing MTPS amount caused a slight increase in gel fraction and decreased the tensile strength of nanocomposite. Also, MTPS could increase the elongation at break of nanocomposite and improve the biodegradation. Nanoclay had no effect on the gel fraction, but it improved tensile strength. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Fabrication and application of responsive polymer surfaces on planar substrates and colloidal particles

    Science.gov (United States)

    Lupitskyy, Robert

    2009-11-01

    In the present dissertation, the problem of controlling interactions of material surfaces with the environment was addressed. Using chemical modification of surfaces with responsive polymers, it is possible to use external stimuli to regulate surface wettability, protein adsorption, stability, and interfacial properties of colloidal particles. The research work presented in this dissertation consists of four independent parts. In the first part (Chapter II), the responsive behavior of a novel heteroarm star-copolymer, poly(2-vinylpyridine)-star-poly(styrene) (PS7-P2VP7), was investigated. For grafted layers of PS7-P2VP7,surface composition, morphology, and wettability can be reversibly changed by treatment with solvents of different thermodynamic quality. Grafted layers of the star-copolymer exhibit a pronounced solvent-dependent phase segregation characteristic and behave similarly to mixed polymer brushes with incompatible components. In the second part (Chapter III), the regulation of fibrinogen adsorption by changing surface composition and microstructure of a mixed polymer brush was explored. The brush is a combination of a protein-repelling component, poly(ethylene glycol), and a protein-attracting component, poly(acrylic acid)-b-polystyrene. Treatment with different organic solvents changes the degree of adsorption of a test protein, fibrinogen, whereas treatment with calcium chloride solution results in virtually no protein adsorption at all. Studies of brush morphology and brush extension in aqueous medium revealed that treatment with different solvents results in different size and distribution of polystyrene domains, which in turn affects the adsorption of fibrinogen. In the third part (Chapter IV), a responsive colloidal system was developed by grafting poly(styrene-b-2-vinylpyridine-b-ethylene oxide) triblock copolymer onto the surface of 200 nm silica particles. This type of grafted polymer layer is both pH- and solvent-sensitive. These properties

  11. Antibacterial Efficiency of Hydroxyapatite Biomaterials with Biodegradable Polylactic Acid and Polycaprolactone Polymers Saturated with Antibiotics / Bionoārdāmu Polimēru Saturošu Un Ar Antibiotiskajām Vielām Piesūcinātu Biomateriālu Antibakteriālās Efektivitātes Noteikšana

    Directory of Open Access Journals (Sweden)

    Kroiča Juta

    2016-08-01

    Full Text Available Infections continue to spread in all fields of medicine, and especially in the field of implant biomaterial surgery, and not only during the surgery, but also after surgery. Reducing the adhesion of bacteria could decrease the possibility of biomaterial-associated infections. Bacterial adhesion could be reduced by local antibiotic release from the biomaterial. In this in vitro study, hydroxyapatite biomaterials with antibiotics and biodegradable polymers were tested for their ability to reduce bacteria adhesion and biofilm development. This study examined the antibacterial efficiency of hydroxyapatite biomaterials with antibiotics and biodegradable polymers against Staphylococcus epidermidis and Pseudomonas aeruginosa. The study found that hydroxyapatite biomaterials with antibiotics and biodegradable polymers show longer antibacterial properties than hydroxyapatite biomaterials with antibiotics against both bacterial cultures. Therefore, the results of this study demonstrated that biomaterials that are coated with biodegradable polymers release antibiotics from biomaterial samples for a longer period of time and may be useful for reducing bacterial adhesion on orthopedic implants.

  12. Macroporous Polymers with Hierarchical Pore Structure from Emulsion Templates Stabilised by Both Particles and Surfactants.

    Science.gov (United States)

    Wong, Ling L Ching; Ikem, Vivian O; Menner, Angelika; Bismarck, Alexander

    2011-10-04

    Inspired by natural porous materials, such as wood, bamboo and spongy bone consisting of individual structural units that are hierarchically arranged to optimise mechanical properties such as strength and toughness, synthetic macroporous polymers with enhanced physical properties were created by emulsion templating. Hierarchical poly(merised) high internal phase emulsions (HIPE) were created from HIPEs stabilised simultaneously by particles and a surfactant. In these HIPEs, surfactant stabilised and particle stabilised water droplets coexist, which upon polymerisation of the minority oil phase gives rise to macroporous polymers with a hierarchical pore structure. An improvement of the mechanical properties of our hierarchically structured macroporous polymers at equal porosity was observed, due to a more efficient packing of pores in a configuration that improves mechanical strength despite the presence of interconnecting pore throats. Moreover, the permeability of the hierarchically structured polyHIPEs are exceeding those measured for conventional polyHIPEs made from surfactant only stabilised HIPEs. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Synthesis and characterization of new functionalized polymer-Fe3O4 nanocomposite particles

    Directory of Open Access Journals (Sweden)

    A. Bukowska

    2017-01-01

    Full Text Available In this study, Fe3O4 nanoparticles (NPs were functionalized with copolymer or terpolymer bearing glycidyl methacrylate (GMA moieties making them suitable for potential applications as drug delivery systems (DDS. For this purpose, the surface of magnetic nanoparticles was first coated with 3-(trimethoxysilyl propyl methacrylate (MPS by a silanization reaction to introduce reactive methacrylate groups onto the surface. Subsequently, monomers were grafted onto the surface of modified-MPS particles via two polymerization methods: seed emulsion (GMA, divinylbenzene, DVB, and styrene, S and distillation – precipitation (GMA and DVB. The obtained nanocomposite particles were characterized by FTIR (Fourier transform infrared spectroscopy, DR UV-Vis (diffuse reflectance ultraviolet – visible spectroscopy, TEM (transmission electron microscopy combined with EDS (energy dispersive X-ray spectroscopy analysis and DLS (dynamic light scattering. FTIR spectroscopy showed that indeed a polymer – Fe3O4@MPS composite was obtained. TEM and EDS analysis showed that the seed emulsion method resulted in nanosized, 100 nm Fe3O4@MPS core/polymer shell NPs, forming long chains. On the contrary, the distillation – precipitation method caused the formation of an inverted structure, i.e. polymer core coated by a Fe3O4@MPS shell, which exhibited a very coarse size distribution varying from several hundreds to over 2 µm.

  14. Change in surface of polymer materials upon irradiation of accelerated micro-particles

    Science.gov (United States)

    Kudo, Hisaaki; Tadokoro, Masashi; Narita, Shintaro; Matsuoka, Leo; Muroya, Yusa; Katsumura, Yosuke

    2005-07-01

    As a new method of use of a particle accelerator (ionizing radiation generator), we irradiated accelerated micro-particles of silver (Ag) onto polymer materials such as polyimides, glass, ceramics and semi-conductors. The particles can be generated at a Van de Graaff electrostatic accelerator operating at 1-3 MV. The velocity was around 1-10 km/s, size of diameter was about 1-10 μm and charge was about 1-2 μC. We investigated the change in surface of materials upon irradiation, by using laser microscope, atomic force microscope and scanning electron microscope. Crater-shaped irradiation spots having limb structure were found, and their diameter and depth were evaluated, ranging in a few micrometers. The planar distribution of the projectile around the irradiation spot was examined with energy dispersive X-ray spectroscopy. Correlation between size of the irradiation spots and kinetic energy of the accelerated micro-particles was investigated, and compared with an empirical formula and molecular dynamics study. Numerical simulation dealing with dynamic behaviour of elastic structure was carried out based on SPH (Smoothed Particle Hydrodynamics) method, a kind of (virtual) particle method. The simulation also found that a crater-shaped spot having limb structure is formed upon collision of the accelerated projectile with the target-materials. The results of simulation were compared with the experimental observations. These experiment and simulation are important for the evaluation of damages and resistance of polymer materials used in the space, such as the thermal control material, and cover glass of solar cells etc., towards space debris and dusts. It would be complement the on-ground radiation resistant tests on the materials conducted by using electron and ion beam accelerators.

  15. Control of conducting polymer actuators without physical feedback: simulated feedback control approach with particle swarm optimization

    Science.gov (United States)

    Xiang, Xingcan; Mutlu, Rahim; Alici, Gursel; Li, Weihua

    2014-03-01

    Conducting polymer actuators have shown significant potential in articulating micro instruments, manipulation devices, and robotics. However, implementing a feedback control strategy to enhance their positioning ability and accuracy in any application requires a feedback sensor, which is extremely large in size compared to the size of the actuators. Therefore, this paper proposes a new sensorless control scheme without the use of a position feedback sensor. With the help of the system identification technique and particle swarm optimization, the control scheme, which we call the simulated feedback control system, showed a satisfactory command tracking performance for the conducting polymer actuator’s step and dynamic displacement responses, especially under a disturbance, without needing a physical feedback loop, but using a simulated feedback loop. The primary contribution of this study is to propose and experimentally evaluate the simulated feedback control scheme for a class of the conducting polymer actuators known as tri-layer polymer actuators, which can operate both in dry and wet media. This control approach can also be extended to other smart actuators or systems, for which the feedback control based on external sensing is impractical.

  16. Control of conducting polymer actuators without physical feedback: simulated feedback control approach with particle swarm optimization

    International Nuclear Information System (INIS)

    Xiang, Xingcan; Mutlu, Rahim; Alici, Gursel; Li, Weihua

    2014-01-01

    Conducting polymer actuators have shown significant potential in articulating micro instruments, manipulation devices, and robotics. However, implementing a feedback control strategy to enhance their positioning ability and accuracy in any application requires a feedback sensor, which is extremely large in size compared to the size of the actuators. Therefore, this paper proposes a new sensorless control scheme without the use of a position feedback sensor. With the help of the system identification technique and particle swarm optimization, the control scheme, which we call the simulated feedback control system, showed a satisfactory command tracking performance for the conducting polymer actuator’s step and dynamic displacement responses, especially under a disturbance, without needing a physical feedback loop, but using a simulated feedback loop. The primary contribution of this study is to propose and experimentally evaluate the simulated feedback control scheme for a class of the conducting polymer actuators known as tri-layer polymer actuators, which can operate both in dry and wet media. This control approach can also be extended to other smart actuators or systems, for which the feedback control based on external sensing is impractical. (paper)

  17. An atomic finite element model for biodegradable polymers. Part 2. A model for change in Young's modulus due to polymer chain scission.

    Science.gov (United States)

    Gleadall, Andrew; Pan, Jingzhe; Kruft, Marc-Anton

    2015-11-01

    Atomic simulations were undertaken to analyse the effect of polymer chain scission on amorphous poly(lactide) during degradation. Many experimental studies have analysed mechanical properties degradation but relatively few computation studies have been conducted. Such studies are valuable for supporting the design of bioresorbable medical devices. Hence in this paper, an Effective Cavity Theory for the degradation of Young's modulus was developed. Atomic simulations indicated that a volume of reduced-stiffness polymer may exist around chain scissions. In the Effective Cavity Theory, each chain scission is considered to instantiate an effective cavity. Finite Element Analysis simulations were conducted to model the effect of the cavities on Young's modulus. Since polymer crystallinity affects mechanical properties, the effect of increases in crystallinity during degradation on Young's modulus is also considered. To demonstrate the ability of the Effective Cavity Theory, it was fitted to several sets of experimental data for Young's modulus in the literature. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Open pore biodegradable matrices formed with gas foaming.

    Science.gov (United States)

    Harris, L D; Kim, B S; Mooney, D J

    1998-12-05

    Engineering tissues utilizing biodegradable polymer matrices is a promising approach to the treatment of a number of diseases. However, processing techniques utilized to fabricate these matrices typically involve organic solvents and/or high temperatures. Here we describe a process for fabricating matrices without the use of organic solvents and/or elevated temperatures. Disks comprised of polymer [e.g., poly (D,L-lactic-co-glycolic acid)] and NaCl particles were compression molded at room temperature and subsequently allowed to equilibrate with high pressure CO2 gas (800 psi). Creation of a thermodynamic instability led to the nucleation and growth of gas pores in the polymer particles, resulting in the expansion of the polymer particles. The polymer particles fused to form a continuous matrix with entrapped salt particles. The NaCl particles subsequently were leached to yield macropores within the polymer matrix. The overall porosity and level of pore connectivity were regulated by the ratio of polymer/salt particles and the size of salt particles. Both the compressive modulus (159+/-130 kPa versus 289+/-25 kPa) and the tensile modulus (334+/-52 kPa versus 1100+/-236 kPa) of the matrices formed with this approach were significantly greater than those formed with a standard solvent casting/particulate leaching process. The utility of these matrices was demonstrated by engineering smooth muscle tissue in vitro with them. This novel process, a combination of high pressure gas foaming and particulate leaching techniques, allows one to fabricate matrices with a well controlled porosity and pore structure. This process avoids the potential negatives associated with the use of high temperatures and/or organic solvents in biomaterials processing.

  19. Intravascular imaging comparison of two metallic limus-eluting stents abluminally coated with biodegradable polymers: IVUS and OCT results of the DESTINY trial.

    Science.gov (United States)

    Costa, J Ribamar; Chamié, Daniel; Abizaid, Alexandre A C; Ribeiro, Expedito; Meireles, George C; Prudente, Maurício; Campos, Carlos A; Castro, Juliana P; Costa, Ricardo; Lemos, Pedro A

    2017-02-01

    We sought to compare, by means of IVUS and OCT imaging, the performance of a novel sirolimus-eluting drug-eluting stent (DES) with biodegradable polymer (Inspiron™) to the Biomatrix™ DES. From the DESTINY trial, a total of 70 randomized patients (2:1) were enrolled in the IVUS substudy (Inspiron™, n = 46; Biomatrix™: n = 20) while 25 patients were evaluated with OCT (Inspiron™, n = 19; Biomatrix™: n = 06) at 9-month follow-up. The main endpoints were % of neointimal tissue obstruction (IVUS) and neointimal stut coverage (OCT) at 9 months. Patients treated with both DES had very little NIH formation at 9 months either by IVUS (% of NIH obstruction of 4.9 ± 4.1 % with Inspiron™ vs. 2.7 ± 2.9 % with Biomatrix™, p = 0.03) or by OCT (neointimal thickness of 144.2 ± 72.5 µm Inspiron™ vs. 115.0 ± 53.9 µm with Biomatrix™, p = 0.45). Regarding OCT strut-level assessment, again both devices showed excellent 9-month performance, with high rates of strut coverage (99.49 ± 1.01 % with Inspiron™ vs. 97.62 ± 2.21 % with Biomatrix™, p < 0.001) and very rare malapposition (0.29 ± 1.06 % with Inspiron™ vs. 0.53 ± 0.82 % with Biomatrix™, p = 0.44). Patients with any uncovered struts were more frequently identified in the Biomatrix™ group (9.78 ± 7.13 vs. 2.29 ± 3.91 %, p < 0.001). In the present study, midterm IVUS and OCT evaluations showed that both new generation DES with biodegradable polymer were effective in terms of suppressing excessive neointimal response, with very high rates of apposed and covered struts, suggesting a consistent and benign healing pattern.

  20. Gender difference on five-year outcomes of EXCEL biodegradable polymer-coated sirolimus-eluting stents implantation: results from the CREATE study.

    Science.gov (United States)

    Zhang, Lei; Qiao, Bing; Han, Ya-Ling; Li, Yi; Xu, Kai; Zhang, Quan-Yu; Yang, Li-Xia; Liu, Hui-Liang; Xu, Bo; Gao, Run-Lin

    2013-03-01

    The gender difference on long-term outcome in unselected patients after percutaneous coronary intervention (PCI) has not yet been fully investigated. This study aimed to evaluate the gender difference on five-year outcomes following EXCEL biodegradable polymer-coated sirolimus-eluting stenting in patients with coronary disease. A total of 2077 "all comers", consisting of 1528 (73.6%) men and 549 (26.4%) women, who were exclusively treated with EXCEL coronary stents were enrolled in the prospective CREATE study at 59 centers from four countries. After propensity score matching, the baseline characteristics of the two groups were well matched. Recommended antiplatelet regimen was clopidogrel and aspirin for six months followed by chronic aspirin therapy. The primary outcome that was the rate of major adverse cardiac events (MACE), defined as a composite of cardiac mortality, non-fatal myocardial infarction (MI) and target lesion revascularization (TLR), and stent thrombosis (ST) at five years were compared between the two gender groups. In the two groups, women had higher proportions of clinical risk factors, such as being elderly, diabetes mellitus, hypertension and hyperlipidemia, compared to men. Besides, the mean target vessel number per patient was higher and the mean reference vessel diameter smaller for women. Men had higher risks of cardiac death (3.7% vs. 1.6%, P = 0.021) and MACE (8.4% vs. 4.7%, P = 0.004) at five years compared with women. However, the cumulative hazards of non-fatal MI and TLR were similar between men and women. The incidence of Academic Research Consortium (ARC) definite or probable stent thrombosis was similar between the two groups (1.3% vs. 1.0%, P = 0.639). Prolonged clopidogrel therapy (>6 months) did not reduce the cumulative hazards of ST from six months to five years in both men (χ(2) = 0.098, log rank P = 0.754) and women (χ(2) = 2.043, log rank P = 0.153) patients. Women had a lower MACE and cardiac death rate than men after

  1. Preparation of porous structures with shape memory properties from biodegradable polymeric networks

    NARCIS (Netherlands)

    Sharifi, Shahriar; Blanquer, Sebastien; Grijpma, Dirk W.

    2012-01-01

    Preparing porous biodegradable structures from shape memory polymers can combine the structure-defining properties of porous structures with the minimally invasive implanting possibilities of shape memory polymers. In this study, porous biodegradable shape memory structures were prepared using

  2. Nanoscale Design of Nano-Sized Particles in Shape-Memory Polymer Nanocomposites Driven by Electricity

    Directory of Open Access Journals (Sweden)

    Kai Yu

    2013-09-01

    Full Text Available In the last few years, we have witnessed significant progress in developing high performance shape memory polymer (SMP nanocomposites, in particular, for shape recovery activated by indirect heating in the presence of electricity, magnetism, light, radio frequency, microwave and radiation, etc. In this paper, we critically review recent findings in Joule heating of SMP nanocomposites incorporated with nanosized conductive electromagnetic particles by means of nanoscale control via applying an electro- and/or magnetic field. A few different nanoscale design principles to form one-/two-/three- dimensional conductive networks are discussed.

  3. Novel colloidal system: Magnetite-polymer particles/lyotropic liquid crystal under magnetic field

    Science.gov (United States)

    Mănăilă-Maximean, D.; Cîrtoaje, C.; Dănilă, O.; Donescu, D.

    2017-09-01

    We obtained a new highly ordered colloidal composite using specially manufactured magnetite-polymer nanoparticles and lyotropic liquid crystal. A good compatibility between the components was ensured by the functionalization of the particles during their synthesis. We studied the laser light transmission for the mixtures filled in sandwich-glass cells with homeotropic and planar treatment of the surfaces under external magnetic field. The Fréedericksz transition critical field was estimated, and its' behavior was compared to our new theoretical model based on the Brochard-de Gennes one.

  4. Viabilidade celular de nanofibras de polímeros biodegradáveis e seus nanocompósitos com argila montmorilonita Cell viability of nanofibers from biodegradable polymers and their nanocomposites with montmorillonite

    Directory of Open Access Journals (Sweden)

    Alfredo M. Goes

    2012-01-01

    Full Text Available Mantas não tecidas de nanofibras de três polímeros biodegradáveis poli(ácido láctico, PDLLA, poli(Ε-caprolactona, PCL, e poli(butileno adipato-co-tereftalato, PBAT e seus nanocompósitos com uma nanoargila montmorilonita (MMT foram produzidas por eletrofiação. A morfologia, o comportamento térmico e a estrutura interna das nanofibras foram analisados por microscopia eletrônica de varredura e transmissão, calorimetria diferencial de varredura e difração de raios X, respectivamente. Observou-se que as nanofibras dos nanocompósitos possuíam diâmetros menores do que os correspondentes polímeros puros e que as nanofibras de PBAT puro e de PBAT/MMT apresentavam a menor cristalinidade de todas as mantas. A viabilidade celular de todas as nanofibras foi analisada pela técnica de redução do sal de tetrazolium pelo complexo enzimático piruvato desidrogenase presente na matriz de mitocôndrias (teste MTT. Os resultados mostraram que nenhuma manta nanofibrílica apresentou toxicidade às células e que as nanofibras de PBAT puro e seu nanocompósito propiciaram ainda um ambiente mais favorável ao desenvolvimento celular de fibroblastos de cardiomiócitos do que as condições oferecidas pelo controles, provavelmente por apresentarem menores diâmetros e baixa cristalinidade em relação às demais nanofibras. Estes resultados mostram o potencial de uso destas mantas nanofibrílicas como suportes de crescimento celular.Non-woven mats of nanofibers of three biodegradable polymers, viz. poly(lactic acid, PDLLA, poly(Ε-caprolactone, PCL, and poly(butylene adipate-co-terephthalate, PBAT, and their nanocomposites with montmorillonite nanoclay (MMT were produced by electrospinning. The morphology, thermal behavior and internal structure of the nanofibers were analyzed by scanning and transmission electron microscopy, differential scanning calorimetry and wide angle X-ray diffraction, respectively. The nanofibers of the nanocomposites had

  5. Development of partially biodegradable foams from PP/HMSPP blends with natural and synthetic polymers; Desenvolvimento de espumas parcialmente biodegradaveis a partir de blendas de PP/HMSPP com polimeros naturais e sinteticos

    Energy Technology Data Exchange (ETDEWEB)

    Cardoso, Elizabeth Carvalho Leite

    2014-07-01

    Polymers are used in various application and in different industrial areas providing enormous quantities of wastes in environment. Among diverse components of residues in landfills are polymeric materials, including Polypropylene, which contribute with 20 to 30% of total volume of solid residues. As polymeric materials are immune to microbial degradation, they remain in soil and in landfills as a semi-permanent residue. Environmental concerning in litter reduction is being directed to renewable polymers development for manufacturing of polymeric foams. Foamed polymers are considered future materials, with a wide range of applications; high density structural foams are specially used in civil construction, in replacement of metal, woods and concrete with a final purpose of reducing materials costs. At present development, it was possible the incorporation of PP/HMSPP polymeric matrix blends with sugarcane bagasse, PHB and PLA, in structural foams production. Thermal degradation at 100, 120 and 160 deg C temperatures was not enough to induce biodegradability. Gamma irradiation degradation, at 50, 100, 200 and 500 kGy showed effective for biodegradability induction. Irradiated bagasse blends suffered surface erosion, in favor of water uptake and consequently, a higher biodegradation in bulk structure. (author)

  6. High-molecular-weight polymers containing biodegradable disulfide bonds: synthesis and in vitro verification of intracellular degradation

    Czech Academy of Sciences Publication Activity Database

    Etrych, Tomáš; Kovář, Lubomír; Šubr, Vladimír; Braunová, Alena; Pechar, Michal; Chytil, Petr; Říhová, Blanka; Ulbrich, Karel

    2010-01-01

    Roč. 25, č. 1 (2010), s. 5-26 ISSN 0883-9115 R&D Projects: GA AV ČR IAA400500806; GA AV ČR KAN200200651 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z50200510 Keywords : water -soluble polymers * reductive degradation * HPMA copolymers Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.610, year: 2010

  7. Tissue response to poly(L-lactic acid)-based blend with phospholipid polymer for biodegradable cardiovascular stents.

    Science.gov (United States)

    Kim, Hyung Il; Ishihara, Kazuhiko; Lee, Seungbok; Seo, Ji-Hun; Kim, Hye Young; Suh, Dongwhan; Kim, Min Uk; Konno, Tomohiro; Takai, Madoka; Seo, Jeong-Sun

    2011-03-01

    A temporary cardiovascular stent device by bioabsorbable materials might reduce late stent thrombosis. A water-soluble amphiphilic phospholipid polymer bearing phosphorylcholine groups (PMB30W) was blended with a high-molecular-weight poly(l-lactic acid) (PLLA) to reduce unfavorable tissue responses at the surface. The PLLA implants and the polymer blend (PLLA/PMB30W) implants were inserted into subcutaneous tissues of rats, the infrarenal aorta of rats, and the internal carotid arteries of rabbits. After 6 months subcutaneous implantation, the PLLA/PMB30W maintained high density of phosphorylcholine groups on the surface without a significant bioabsorption. After intravascular implantation, the cross-sectional areas of polymer tubing with diameters less than 1.6 mm were histomorphometrically measured. Compared to the PLLA tubing, the PLLA/PMB30W tubing significantly reduced the thrombus formation during 30 d of implantation. Human peripheral blood mononuclear cells were cultured on the PLLA and the PLLA/PMB30W to compare inflammatory reactions. Enzyme-linked immunosorbent assay quantified substantially decreased proinflammatory cytokines in the case of the PLLA/PMB30W. They were almost the same level as the negative controls. Thus, we conclude that the phosphorylcholine groups could reduce tissue responses significantly both in vivo and in vitro, and the PLLA/PMB30W is a promising material for preparing temporary cardiovascular stent devices. Copyright © 2010 Elsevier Ltd. All rights reserved.

  8. Strong electroactive biodegradable shape memory polymer networks based on star-shaped polylactide and aniline trimer for bone tissue engineering.

    Science.gov (United States)

    Xie, Meihua; Wang, Ling; Ge, Juan; Guo, Baolin; Ma, Peter X

    2015-04-01

    Preparation of functional shape memory polymer (SMP) for tissue engineering remains a challenge. Here the synthesis of strong electroactive shape memory polymer (ESMP) networks based on star-shaped polylactide (PLA) and aniline trimer (AT) is reported. Six-armed PLAs with various chain lengths were chemically cross-linked to synthesize SMP. After addition of an electroactive AT segment into the SMP, ESMP was obtained. The polymers were characterized by (1)H NMR, GPC, FT-IR, CV, DSC, DMA, tensile test, and degradation test. The SMP and ESMP exhibited strong mechanical properties (modulus higher than GPa) and excellent shape memory performance: short recovery time (several seconds), high recovery ratio (over 94%), and high fixity ratio (almost 100%). Moreover, cyclic voltammetry test confirmed the electroactivity of the ESMP. The ESMP significantly enhanced the proliferation of C2C12 cells compared to SMP and linear PLA (control). In addition, the ESMP greatly improved the osteogenic differentiation of C2C12 myoblast cells compared to PH10 and PLA in terms of ALP enzyme activity, immunofluorescence staining, and relative gene expression by quantitative real-time polymerase chain reaction (qRT-PCR). These intelligent SMPs and electroactive SMP with strong mechanical properties, tunable degradability, good electroactivity, biocompatibility, and enhanced osteogenic differentiation of C2C12 cells show great potential for bone regeneration.

  9. Latent heat storage in a fixed-bed packed with cross-linked polymer particles

    Science.gov (United States)

    Morita, Hiroki; Miyatake, Osamu

    Experimental and numerical analyses were carried out to investigate the discharge characteristics of a fixed-bed, using form-stable cross-linked cylindrical polymer particles as a phase change type of heat storage material and ethylene glycol as heat transfer fluid. Firstly, particle-to-fluid heat transfer coefficient in a fixed-bed, essential for analyzing the discharge characteristics of the latent heat storage column, were evaluated experimentally using Schumann's extended theory, and an empirical formula for estimating the heat transfer coefficient was presented. Secondly, by using the empirical formula, the transient temperature distribution in the column and the transient response of the outlet temperature of the heat transfer fluid were calculated numerically, and the latter was compared with measurements of the outlet temperature of the fluid. The numerical results were found to be in good agreement with the experimental results.

  10. Alumina particles doped in a polymer film act as scatterers for random laser generation

    Science.gov (United States)

    Cao, Dan; Huang, Dengfeng; Zhang, Xiaoqiang; Zeng, Shumao; Parbey, Joseph; Liu, Shenye; Wang, Chuanke; Yi, Tao; Li, Tingshuai

    2018-02-01

    Lasing can be achieved with a system that has randomly distributed particles that act as scatterers in polymer films doped with laser dyes; a strict resonant cavity is not required. In this study, alumina particles and Rhodamine 6G dye were dispersed in polyvinyl pyrrolidone solutions as slurry to prepare thin films by a spin-coating method. These films were then pumped as a laser generator using a pulsed Nd:YLF laser. The results indicate that film thickness had an obvious affect on laser emission, and the lasing intensity increased with the pump energy, which tended to increase and then decrease with film thickness. An optical model based on the fabricated films was established to analyze light coupling with the films and possible distribution of light in films.

  11. Inhibition of surface crystallisation of amorphous indomethacin particles in physical drug-polymer mixtures

    DEFF Research Database (Denmark)

    Priemel, Petra A; Laitinen, Riikka; Barthold, Sarah

    2013-01-01

    or Soluplus(®) in 3:1, 1:1 and 1:3 (w/w) ratios were stored at 30°C and 23 or 42% RH. Samples were analysed during storage by X-ray powder diffraction, thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy (SEM). IMC Eudragit(®) mixtures showed higher physical......Surface coverage may affect the crystallisation behaviour of amorphous materials. This study investigates crystallisation inhibition in powder mixtures of amorphous drug and pharmaceutical excipients. Pure amorphous indomethacin (IMC) powder and physical mixtures thereof with Eudragit(®) E...... through reduced IMC surface molecular mobility. Polymer particles may also mechanically hinder crystal growth outwards from the surface. This work highlights the importance of microparticulate surface coverage of amorphous drug particles on their stability....

  12. Bright conjugated polymer nanoparticles containing a biodegradable shell produced at high yields and with tuneable optical properties by a scalable microfluidic device.

    Science.gov (United States)

    Abelha, T F; Phillips, T W; Bannock, J H; Nightingale, A M; Dreiss, C A; Kemal, E; Urbano, L; deMello, J C; Green, M; Dailey, L A

    2017-02-02

    This study compares the performance of a microfluidic technique and a conventional bulk method to manufacture conjugated polymer nanoparticles (CPNs) embedded within a biodegradable poly(ethylene glycol) methyl ether-block-poly(lactide-co-glycolide) (PEG 5K -PLGA 55K ) matrix. The influence of PEG 5K -PLGA 55K and conjugated polymers cyano-substituted poly(p-phenylene vinylene) (CN-PPV) and poly(9,9-dioctylfluorene-2,1,3-benzothiadiazole) (F8BT) on the physicochemical properties of the CPNs was also evaluated. Both techniques enabled CPN production with high end product yields (∼70-95%). However, while the bulk technique (solvent displacement) under optimal conditions generated small nanoparticles (∼70-100 nm) with similar optical properties (quantum yields ∼35%), the microfluidic approach produced larger CPNs (140-260 nm) with significantly superior quantum yields (49-55%) and tailored emission spectra. CPNs containing CN-PPV showed smaller size distributions and tuneable emission spectra compared to F8BT systems prepared under the same conditions. The presence of PEG 5K -PLGA 55K did not affect the size or optical properties of the CPNs and provided a neutral net electric charge as is often required for biomedical applications. The microfluidics flow-based device was successfully used for the continuous preparation of CPNs over a 24 hour period. On the basis of the results presented here, it can be concluded that the microfluidic device used in this study can be used to optimize the production of bright CPNs with tailored properties with good reproducibility.

  13. Biodegradable polymeric nanocarriers for pulmonary drug delivery.

    Science.gov (United States)

    Rytting, Erik; Nguyen, Juliane; Wang, Xiaoying; Kissel, Thomas

    2008-06-01

    Pulmonary drug delivery is attractive for both local and systemic drug delivery as a non-invasive route that provides a large surface area, thin epithelial barrier, high blood flow and the avoidance of first-pass metabolism. Nanoparticles can be designed to have several advantages for controlled and targeted drug delivery, including controlled deposition, sustained release, reduced dosing frequency, as well as an appropriate size for avoiding alveolar macrophage clearance or promoting transepithelial transport. This review focuses on the development and application of biodegradable polymers to nanocarrier-based strategies for the delivery of drugs, peptides, proteins, genes, siRNA and vaccines by the pulmonary route. The selection of natural or synthetic materials is important in designing particles or nanoparticle clusters with the desired characteristics, such as biocompatibility, size, charge, drug release and polymer degradation rate.

  14. Investigation of preparation and mechanisms of a dispersed particle gel formed from a polymer gel at room temperature.

    Directory of Open Access Journals (Sweden)

    Guang Zhao

    Full Text Available A dispersed particle gel (DPG was successfully prepared from a polymer gel at room temperature. The polymer gel system, morphology, viscosity changes, size distribution, and zeta potential of DPG particles were investigated. The results showed that zirconium gel systems with different strengths can be cross-linked within 2.5 h at low temperature. Scanning electron microscopy (SEM, transmission electron microscopy (TEM, and atomic force microscopy (AFM results showed that the particles were polygonal particles with nano-size distribution. According to the viscosity changes, the whole preparation process can be divided into two major stages: the bulk gel cross-linking reaction period and the DPG particle preparation period. A polymer gel with a 3-dimensional network was formed in the bulk gel cross-linking reaction period whereas shearing force and frictional force were the main driving forces for the preparation of DPG particles, and thus affected the morphology of DPG particles. High shearing force and frictional force reduced the particle size distribution, and then decreased the zeta potential (absolute value. The whole preparation process could be completed within 3 h at room temperature. It could be an efficient and energy-saving technology for preparation of DPG particles.

  15. Large accumulation of micro-sized synthetic polymer particles in the sea surface microlayer.

    Science.gov (United States)

    Song, Young Kyoung; Hong, Sang Hee; Jang, Mi; Kang, Jung-Hoon; Kwon, Oh Youn; Han, Gi Myung; Shim, Won Joon

    2014-08-19

    Determining the exact abundance of microplastics on the sea surface can be susceptible to the sampling method used. The sea surface microlayer (SML) can accumulate light plastic particles, but this has not yet been sampled. The abundance of microplastics in the SML was evaluated off the southern coast of Korea. The SML sampling method was then compared to bulk surface water filtering, a hand net (50 μm mesh), and a Manta trawl net (330 μm mesh). The mean abundances were in the order of SML water > hand net > bulk water > Manta trawl net. Fourier transform infrared spectroscopy (FTIR) identified that alkyds and poly(acrylate/styrene) accounted for 81 and 11%, respectively, of the total polymer content of the SML samples. These polymers originated from paints and the fiber-reinforced plastic (FRP) matrix used on ships. Synthetic polymers from ship coatings should be considered to be a source of microplastics. Selecting a suitable sampling method is crucial for evaluating microplastic pollution.

  16. Investigating the particle to fibre transition threshold during electrohydrodynamic atomization of a polymer solution

    Energy Technology Data Exchange (ETDEWEB)

    Husain, O.; Lau, W.; Edirisinghe, M.; Parhizkar, M., E-mail: maryam.parhizkar.09@ucl.ac.uk

    2016-08-01

    Electrohydrodynamic atomization (EHDA) is a key research area for producing micro and nano-sized structures. This process can be categorized into two main operating regimes: electrospraying for particle generation and electrospinning for fibre production. Producing particles/fibres of the desired size or morphology depends on two main factors; properties of the polymeric solution used and the processing conditions including flow rate, applied voltage and collection distance. In this work the particle-fibre transition region was analyzed by changing the polymer concentration of PLGA poly (lactic-co-glycolic acid) in acetone between 2 and 25 wt%. Subsequently the processing conditions were adjusted to study the optimum transition parameters. Additionally the EHDA configuration was also modified by adding a metallic plate to observe the deposition area. The diameter and the distance of the plate from the capillary tip were adjusted to investigate variations in particle and fibre morphologies as well. It was found that complete transition from particles to fibres occurs at 20 wt% indicating concentration to be the dominant criterion. Low flow rates yielded fibres without beads. However the applied voltage and distance between the tip of the nozzle jetting the polymer solution and collector (working distance) did not yield definitive results. Reducing the collector distance and increasing applied voltages produces smooth as well as beaded fibres. Addition of a metal plate reduces particle size by ~ 1 μm; the fibre size increases especially with increasing plate diameter while bead density and size reduces when the disc is fixed closer to the capillary tip. Additionally, the deposition area is reduced by 70% and 57% with the addition of metal plates of 30 mm and 60 mm, respectively. The results indicate that a metal plate can be utilized further to tune the particle/fibre size and morphology and this also significantly increases the yield of EHDA process which is

  17. Development of a Sustainable Release System for a Ranibizumab Biosimilar Using Poly(lactic-co-glycolic acid) Biodegradable Polymer-Based Microparticles as a Platform.

    Science.gov (United States)

    Tanetsugu, Yusuke; Tagami, Tatsuaki; Terukina, Takayuki; Ogawa, Takaya; Ohta, Masato; Ozeki, Tetsuya

    2017-01-01

    Ranibizumab is a humanized monoclonal antibody fragment against vascular endothelial growth factor (VEGF)-A and is widely used to treat age-related macular degeneration (AMD) caused by angiogenesis. Ranibizumab has a short half-life in the eye due to its low molecular weight and susceptibility to proteolysis. Monthly intravitreal injection of a large amount of ranibizumab formulation is a burden for both patients and medical staff. We therefore sought to develop a sustainable release system for treating the eye with ranibizumab using a drug carrier. A ranibizumab biosimilar (RB) was incorporated into microparticles of poly(lactic-co-glycolic acid) (PLGA) biodegradable polymer. Ranibizumab was sustainably released from PLGA microparticles (80+% after 3 weeks). Assay of tube formation by endothelial cells indicated that RB released from PLGA microparticles inhibited VEGF-induced tube formation and this tendency was confirmed by a cell proliferation assay. These results indicate that RB-loaded PLGA microparticles are useful for sustainable RB release and suggest the utility of intraocular sustainable release systems for delivering RB site-specifically to AMD patients.

  18. Solid phase extraction of lead, cadmium and zinc on biodegradable polyhydroxybutyrate diethanol amine (PHB-DEA) polymer and their determination in water and food samples.

    Science.gov (United States)

    Tuzen, Mustafa; Sahiner, Samet; Hazer, Baki

    2016-11-01

    A new biodegradable polyhydroxybutyrate diethanol amine (PHB-DEA) polymer was used as adsorbent for the sensitive and selective separation, preconcentration and determination of Pb(II), Cd(II) and Zn(II) by using atomic absorption spectrometry. Diethyl dithiocarbamate was used as chelating reagent. Analytical parameters such as pH, eluent type and its volume, flow rates of sample solution, ligand amount, sample volume were optimized. Effects of some cations, anions and transition metal ions were also investigated. Enrichment factor and relative standard deviation were found to be 100 and 3%, respectively. The limits of detection based on three times standard deviation of blanks (N=21) were found 1.05μgL(-1) for Pb(II), 0.42μgL(-1) for Cd(II) and 0.13μgL(-1) for Zn(II). Limits of quantification (10s, N=21) were found 3.47μgL(-1) for Pb(II), 1.39μgL(-1) for Cd(II) and 0.43μgL(-1) for Zn(II). Accuracy evaluation of the method was confirmed with analyses of certified reference materials (NIST SRM 1515 Apple leaves, IAEA 336 Lichen, GBW 07605 Tea). Optimized method was applied to tap water and food samples after microwave digestion method. Cadmium and lead values in some samples were found higher than legal limits. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Consistent model reduction of polymer chains in solution in dissipative particle dynamics: Model description

    KAUST Repository

    Moreno Chaparro, Nicolas

    2015-06-30

    We introduce a framework for model reduction of polymer chain models for dissipative particle dynamics (DPD) simulations, where the properties governing the phase equilibria such as the characteristic size of the chain, compressibility, density, and temperature are preserved. The proposed methodology reduces the number of degrees of freedom required in traditional DPD representations to model equilibrium properties of systems with complex molecules (e.g., linear polymers). Based on geometrical considerations we explicitly account for the correlation between beads in fine-grained DPD models and consistently represent the effect of these correlations in a reduced model, in a practical and simple fashion via power laws and the consistent scaling of the simulation parameters. In order to satisfy the geometrical constraints in the reduced model we introduce bond-angle potentials that account for the changes in the chain free energy after the model reduction. Following this coarse-graining process we represent high molecular weight DPD chains (i.e., ≥200≥200 beads per chain) with a significant reduction in the number of particles required (i.e., ≥20≥20 times the original system). We show that our methodology has potential applications modeling systems of high molecular weight molecules at large scales, such as diblock copolymer and DNA.

  20. Ion induced transformation of polymer films into diamond-like carbon incorporating silver nano particles

    International Nuclear Information System (INIS)

    Schwarz, Florian P.

    2010-01-01

    Silver containing diamond-like carbon (DLC) is an interesting material for medical engineering from several points of view. On the one hand DLC provides high mechanical robustness. It can be used as biocompatible and wear resistant coating for joint replacing implants. On the other hand silver has antimicrobial properties, which could reduce post-operative inflammations. However conventional production of Ag-DLC by co-deposition of silver and carbon in a plasma process is problematic since it does not allow for a separate control of nano particle morphology and matrix properties. In this work an alternative production method has been developed to circumvent this problem. In metall-DLC-production by ion implantation into a nano composite, silver nano particles are initially formed in solution and then incorporated within a polymer matrix. Finally the polymer is transformed into DLC by ion implantation. The aspects and single steps of this method were investigated with regard to the resulting material's properties. The goal was to design an economically relevant deposition method. Based on experimental results a model of the transformation process has been established, which has also been implemented in a computer simulation. Finally the antibacterial properties of the material have been checked in a biomedical test. Here a bacterial killing rate of 90% could be achieved. (orig.)

  1. The relevance of molecular weight in the design of amorphous biodegradable polymers with optimized shape memory effect.

    Science.gov (United States)

    Petisco-Ferrero, S; Fernández, J; Fernández San Martín, M M; Santamaría Ibarburu, P A; Sarasua Oiz, J R

    2016-08-01

    The shape memory effect (SME) has long been the focus of interest of many research groups that have studied many facets of it, yet to the authors' knowledge some molecular parameters, such as the molecular weight, have been skipped. Thus, the aim of this work is to offer further insight into the shape memory effect, by disclosing the importance of the molecular weight as the relevant parameter dictating the extension of the rubbery plateau, which is the scenario where the entropic network of entanglements manifests. For this, a set of biodegradable amorphous poly(rac-d,l)lactides have been synthesised by ring opening copolymerization of a racemic mixture of L-and D-lactide. The analysis performed on the synthesised enantiomeric copolylactides includes the determination of molecular weights by means of Gel Permeation Chromatography (GPC), thermal properties by Differential Scanning Calorimetry (DSC), dynamic mechanical analysis (DMA) and rheological tests using small amplitude oscillatory flow analysis. Shape memory properties have been determined by means of specific cyclic thermo-mechanic test protocol. It has been shown that the recovery capacity of amorphous PDLLA is linked to the disentanglement time through an exponential law. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. The critical particle size for enhancing thermal conductivity in metal nanoparticle-polymer composites

    Science.gov (United States)

    Lu, Zexi; Wang, Yan; Ruan, Xiulin

    2018-02-01

    Polymers used as thermal interface materials are often filled with high-thermal conductivity particles to enhance the thermal performance. Here, we have combined molecular dynamics and the two-temperature model in 1D to investigate the impact of the metal filler size on the overall thermal conductivity. A critical particle size has been identified above which thermal conductivity enhancement can be achieved, caused by the interplay between high particle thermal conductivity and the added electron-phonon and phonon-phonon thermal boundary resistance brought by the particle fillers. Calculations on the SAM/Au/SAM (self-assembly-monolayer) system show a critical thickness Lc of around 10.8 nm. Based on the results, we define an effective thermal conductivity and propose a new thermal circuit analysis approach for the sandwiched metal layer that can intuitively explain simulation and experimental data. The results show that when the metal layer thickness decreases to be much smaller than the electron-phonon cooling length (or as the "thin limit"), the effective thermal conductivity is just the phonon portion, and electrons do not participate in thermal transport. As the thickness increases to the "thick limit," the effective thermal conductivity recovers the metal bulk value. Several factors that could affect Lc are discussed, and it is discovered that the thermal conductivity, thermal boundary resistance, and the electron-phonon coupling factor are all important in controlling Lc.

  3. Facile hierarchical assembly of gold particle decorated conductive polymer nanofibers for electrochemical sensing

    Science.gov (United States)

    Dai, Minhui; Chen, Juhong; Goddard, Julie M.; Nugen, Sam R.

    2017-02-01

    In this study, we successfully applied vapor-phase polymerization towards the synthesis of PEDOT nanofibers which were subsequently functionalized with gold particles and used as electrodes for electrochemical sensing. Two methods were used to synthesize the PEDOT nanofibers including (1) electrospinning followed by vapor-phase polymerization (EVP), and (2) one-step vapor-phase polymerization (OSVP). The average diameter of EVP fibers was approximately 350 nm, and OSVP was approximately 200 nm. Gold particles (∼500 nm) were synthesized by an oxidation-reduction reaction between gold precursors and residue EDOT monomers on the surface of the PEDOT nanofibers. In order to investigate the electrochemical performance of these electrodes, ascorbic acid was chosen as an analyte model. Our results indicated that PEDOT nanofiber electrodes showed an enhanced response with respect to bare gold electrodes. Furthermore, the OSVP PEDOT nanofibers with gold particles demonstrated the highest sensitivity at low ascorbic acid concentrations. These hierarchically assembled, gold particle-decorated, conductive polymer nanofibers were further fabricated into flexible electrodes, demonstrating a potential in advanced applications such as wearable electronics.

  4. Hygral Behavior of Superabsorbent Polymers with Various Particle Sizes and Cross-Linking Densities

    Directory of Open Access Journals (Sweden)

    Kyong-Ku Yun

    2017-11-01

    Full Text Available This study focuses on investigating the effects of particle size and cross-linking density on the hygral behavior of superabsorbent polymers (SAPs, which are increasingly used as an internal curing material for high-performance concrete. Four SAPs with different mean particle diameters and cross-linking densities were tested under controlled wetting and drying conditions to measure free absorption and desorption kinetics. Absorption capacities of SAPs under actual mixing conditions were additionally measured and verified by means of mortar flow and semi-adiabatic hydration heat measurements. In addition, the effects of SAP type and dosage (i.e., 0.2, 0.4, and 0.6% by mass of cement on the mechanical properties of hardened mortar were assessed. The results indicated that: (1 the absorption capacity increased with decreased cross-linking density and increased particle size under both load-free and mixing conditions; and (2 the greater the cross-linking density and the lower the particle size, the shorter the desorption time. It was also confirmed that while the early-age mechanical properties were more related with the gel strength of swollen SAP, the later-age mechanical properties were more affected by the water retention capacity and spatial distribution of SAP in the matrix.

  5. Transparent Conductive Adhesives for Tandem Solar Cells Using Polymer-Particle Composites

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Talysa [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Lee, Benjamin G [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Schnabel, Manuel [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Warren, Emily L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Stradins, Paul [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Tamboli, Adele C [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Van Hest, Marinus F [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2018-02-14

    Transparent conductive adhesives (TCAs) can enable conductivity between two substrates, which is useful for a wide range of electronic devices. Here, we have developed a TCA composed of a polymer-particle blend with ethylene-vinyl acetate as the transparent adhesive and metal-coated flexible poly(methyl methacrylate) microspheres as the conductive particles that can provide conductivity and adhesion regardless of the surface texture. This TCA layer was designed to be nearly transparent, conductive in only the out-of-plane direction, and of practical adhesive strength to hold the substrates together. The series resistance was measured at 0.3 and 0.8 O cm2 for 8 and 0.2% particle coverage, respectively, while remaining over 92% was transparent in both cases. For applications in photovoltaic devices, such as mechanically stacked multijunction III-V/Si cells, a TCA with 1% particle coverage will have less than 0.5% power loss due to the resistance and less than 1% shading loss to the bottom cell.

  6. Steady shear rheometry of dissipative particle dynamics models of polymer fluids in reverse Poiseuille flow.

    Science.gov (United States)

    Fedosov, Dmitry A; Karniadakis, George Em; Caswell, Bruce

    2010-04-14

    Polymer fluids are modeled with dissipative particle dynamics (DPD) as undiluted bead-spring chains and their solutions. The models are assessed by investigating their steady shear-rate properties. Non-Newtonian viscosity and normal stress coefficients, for shear rates from the lower to the upper Newtonian regimes, are calculated from both plane Couette and plane Poiseuille flows. The latter is realized as reverse Poiseuille flow (RPF) generated from two Poiseuille flows driven by uniform body forces in opposite directions along two-halves of a computational domain. Periodic boundary conditions ensure the RPF wall velocity to be zero without density fluctuations. In overlapping shear-rate regimes the RPF properties are confirmed to be in good agreement with those calculated from plane Couette flow with Lees-Edwards periodic boundary conditions (LECs), the standard virtual rheometer for steady shear-rate properties. The concentration and the temperature dependence of the properties of the model fluids are shown to satisfy the principles of concentration and temperature superposition commonly employed in the empirical correlation of real polymer-fluid properties. The thermodynamic validity of the equation of state is found to be a crucial factor for the achievement of time-temperature superposition. With these models, RPF is demonstrated to be an accurate and convenient virtual rheometer for the acquisition of steady shear-rate rheological properties. It complements, confirms, and extends the results obtained with the standard LEC configuration, and it can be used with the output from other particle-based methods, including molecular dynamics, Brownian dynamics, smooth particle hydrodynamics, and the lattice Boltzmann method.

  7. Adsorption of human IgG on to poly(N-isopropylacrylamide)-based polymer particles.

    Science.gov (United States)

    Silva, Claudia S O; Baptista, Ricardo P; Santos, Andrea M; Martinho, José M G; Cabral, Joaquim M S; Taipa, M Angela

    2006-12-01

    Thermosensitive poly(N-isopropylacrylamide)-based polymer particles were synthesised, and screened for the adsorption of human immunoglobulin G (hIgG). At pH 9 the adsorption on microgel particles was strongly affected by temperature, approximately 40 mg hIgG/g support (90% of initial hIgG) being adsorbed at 40 degrees C but only 10% of initial hIgG at 25 degrees C. At pH 5 the maximum adsorbed amount (20 mg hIgG/g support) was similar for both temperatures. The adsorption of hIgG on to charged poly(methyl methacrylate)/poly(N-isopropylacrylamide) core-shell latexes was negligible (5-10 mg hIgG/g support) at the same temperature and pH conditions. The lower adsorption of hIgG onto the core-shell particles is explained by steric interactions due to the small size of the shell.

  8. Polymer nanocomposite particles of S-nitrosoglutathione: A suitable formulation for protection and sustained oral delivery.

    Science.gov (United States)

    Wu, Wen; Gaucher, Caroline; Fries, Isabelle; Hu, Xian-Ming; Maincent, Philippe; Sapin-Minet, Anne

    2015-11-10

    S-nitrosoglutathione (GSNO) is a nitric oxide (NO) donor with therapeutic potential for cardiovascular disease treatment. Chronic oral treatment with GSNO is limited by high drug sensitivity to the environment and limited oral bioavailability, requiring the development of delivery systems able to sustain NO release. The present work describes new platforms based on polymer nanocomposite particles for the delivery of GSNO. Five types of optimized nanocomposite particles have been developed (three based on chitosan, two based on alginate sodium). Those nanocomposite particles encapsulate GSNO with high efficiency from 64% to 70% and an average size of 13 to 61 μm compatible with oral delivery. Sustained release of GSNO in vitro was achieved. Indeed, chitosan nanocomposites discharged their payload within 24h; whereas alginate nanocomposites released GSNO more slowly (10% of GSNO was still remaining in the dosage form after 24h). Their cytocompatibility toward intestinal Caco-2 cells (MTT assay) was acceptable (IC50: 6.07 ± 0.07-9.46 ± 0.08 mg/mL), demonstrating their suitability as oral delivery systems for GSNO. These delivery systems presented efficient GSNO loading and sustained release as well as cytocompatibility, showing their promise as a means of improving the oral bioavailability of GSNO and as a potential new treatment. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Identification of polymer types and additives in marine microplastic particles using pyrolysis-GC/MS and scanning electron microscopy.

    Science.gov (United States)

    Fries, Elke; Dekiff, Jens H; Willmeyer, Jana; Nuelle, Marie-Theres; Ebert, Martin; Remy, Dominique

    2013-10-01

    Any assessment of plastic contamination in the marine environment requires knowledge of the polymer type and the additive content of microplastics. Sequential pyrolysis-gas chromatography coupled to mass spectrometry (Pyr-GC/MS) was applied to simultaneously identify polymer types of microplastic particles and associated organic plastic additives (OPAs). In addition, a scanning electron microscope equipped with an energy-dispersive X-ray microanalyser was used to identify the inorganic plastic additives (IPAs) contained in these particles. A total of ten particles, which were optically identified as potentially being plastics, were extracted from two sediment samples collected from Norderney, a North Sea island, by density separation in sodium chloride. The weights of these blue, white and transparent fragments varied between 10 and 350 μg. Polymer types were identified by comparing the resulting pyrograms with those obtained from the pyrolysis of selected standard polymers. The particles consisted of polyethylene (PE), polypropylene, polystyrene, polyamide, chlorinated PE and chlorosulfonated PE. The polymers contained diethylhexyl phthalate, dibutyl phthalate, diethyl phthalate, diisobutyl phthalate, dimethyl phthalate, benzaldehyde and 2,4-di-tert-butylphenol. Sequential Py-GC/MS was found to be an appropriate tool for identifying marine microplastics for polymer types and OPAs. The IPAs identified were titanium dioxide nanoparticles (TiO2-NPs), barium, sulphur and zinc. When polymer-TiO2 composites are degraded in the marine environment, TiO2-NPs are probably released. Thus, marine microplastics may act as a TiO2-NP source, which has not yet been considered.

  10. First-in-man randomised comparison of the BuMA Supreme biodegradable polymer sirolimus-eluting stent versus a durable polymer zotarolimus-eluting coronary stent: the PIONEER trial.

    Science.gov (United States)

    von Birgelen, Clemens; Asano, Taku; Amoroso, Giovanni; Aminian, Adel; Brugaletta, Salvatore; Vrolix, Mathias; Hernandez-Antolín, Rosana; van de Harst, Pim; Iñiguez, Andres; Janssens, Luc; Smits, Pieter C; Wykrzykowska, Joanna J; Ribeiro, Vasco Gama; Pereira, Hélder; da Silva, Pedro Canas; Piek, Jan J; Onuma, Yoshinobu; Serruys, Patrick W; Sabaté, Manel

    2018-04-20

    A second iteration of a sirolimus-eluting stent (SES) that has a biodegradable PLGA polymer coating with an electrografting base layer on a thin-strut (80 µm) cobalt-chromium platform (BuMA Supreme; SINOMED, Tianjin, China) has been developed. This first-in-man trial aimed to assess the efficacy and safety of the novel device. This randomised, multicentre, single-blinded, non-inferiority trial compared the BuMA Supreme SES versus a contemporary durable polymer zotarolimus-eluting stent (ZES) in terms of angiographic in-stent late lumen loss (LLL) at nine-month follow-up as the primary endpoint. A total of 170 patients were randomly allocated to treatment with either SES (n=83) or ZES (n=87). At nine-month angiographic follow-up, in-stent LLL was 0.29±0.33 mm in the SES group and 0.14±0.37 mm in the ZES group (pnon-inferiority=0.45). The in-stent percent diameter stenosis and the binary restenosis rate of the two treatment arms were similar (19.2±12.0% vs. 16.1±12.6%, p=0.09, and 3.3% vs. 4.4%, p=1.00, respectively). At 12-month clinical follow-up, there was no difference between treatment arms with regard to the device-oriented composite clinical endpoint (4.9% vs. 5.7%; p=0.72). The PIONEER trial did not meet its primary endpoint in terms of in-stent LLL at nine-month follow-up. However, this result did not translate into any increase in restenosis rate or impairment in 12-month clinical outcomes.

  11. Electrical four-point probing of spherical metallic thin films coated onto micron sized polymer particles

    Energy Technology Data Exchange (ETDEWEB)

    Pettersen, Sigurd R., E-mail: sigurd.r.pettersen@ntnu.no, E-mail: jianying.he@ntnu.no; Stokkeland, August Emil; Zhang, Zhiliang; He, Jianying, E-mail: sigurd.r.pettersen@ntnu.no, E-mail: jianying.he@ntnu.no [NTNU Nanomechanical Lab, Department of Structural Engineering, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim (Norway); Kristiansen, Helge [NTNU Nanomechanical Lab, Department of Structural Engineering, Norwegian University of Science and Technology (NTNU), NO-7491 Trondheim (Norway); Conpart AS, Dragonveien 54, NO-2013 Skjetten (Norway); Njagi, John; Goia, Dan V. [Center for Advanced Materials Processing, Clarkson University, Potsdam, New York 13699-5814 (United States); Redford, Keith [Conpart AS, Dragonveien 54, NO-2013 Skjetten (Norway)

    2016-07-25

    Micron-sized metal-coated polymer spheres are frequently used as filler particles in conductive composites for electronic interconnects. However, the intrinsic electrical resistivity of the spherical thin films has not been attainable due to deficiency in methods that eliminate the effect of contact resistance. In this work, a four-point probing method using vacuum compatible piezo-actuated micro robots was developed to directly investigate the electric properties of individual silver-coated spheres under real-time observation in a scanning electron microscope. Poly(methyl methacrylate) spheres with a diameter of 30 μm and four different film thicknesses (270 nm, 150 nm, 100 nm, and 60 nm) were investigated. By multiplying the experimental results with geometrical correction factors obtained using finite element models, the resistivities of the thin films were estimated for the four thicknesses. These were higher than the resistivity of bulk silver.

  12. The use of dielectric spectroscopy for the characterization of polymer-induced flocculation of polystyrene particles

    DEFF Research Database (Denmark)

    Christensen, Peter Vittrup; Keiding, Kristian

    2008-01-01

    in dilute suspensions. Thus, techniques usable for flocculation characterization in high-solids suspensions are desirable. This study investigates the use of dielectric spectroscopy to monitor the flocculation of polystyrene particles with a cationic polymer. The frequency-dependent permittivity is modeled......The flocculation of colloidal suspensions is an important unit operation in many industries, as it greatly improves the performance of solid separation processes. The number of available techniques for evaluating flocculation processes on line is limited, and most of these are only functional...... as a decrease in the magnitude of the dielectric dispersion. The use of dielectric spectroscopy is found to be valuable for assessing flocculation processes in high-solids suspensions, as changes in parameters Such as floc size and charge can be detected....

  13. Drug-eluting stents with biodegradable polymer for the treatment of patients with diabetes mellitus: clinical outcome at 2 years in a large population of patients

    Directory of Open Access Journals (Sweden)

    Wiemer M

    2015-02-01

    Full Text Available Marcus Wiemer,1 Gian Battista Danzi,2 Nick West,3 Vassilios Voudris,4 René Koning,5 Stefan Hoffmann,6 Mario Lombardi,7 Josepa Mauri,8 Rade Babic,9 Fraser Witherow10On behalf of the NOBORI 2 Investigators 1Department of Cardiology, Heart and Diabetes Center North Rhine–Westphalia, Ruhr University Bochum, Bad Oeynhausen, Germany; 2Ospedale Maggiore Policlinico, Milan, Italy; 3Papworth Hospital, Cambridge, UK; 4Onassis Cardiac Surgery Center, Athens, Greece; 5Clinique Saint Hilaire, Rouen, France; 6Vivantes Netzwerk für Gesundheit GmbH, Berlin, Germany; 7Azienda Ospedaliera Villa Sofia, Palermo, Italy; 8Hospital Universitari Germans Trias i Pujol, Badalona, Spain; 9Institute for Cardiovascular Diseases Dedinje, Belgrade, Serbia; 10Dorset County Hospital, Dorchester, UK Objective: This study investigates the safety and efficacy of a third-generation drug-eluting stent (DES with biodegradable polymer in the complex patient population of diabetes mellitus (DM. Clinical trial registration: ISRCTN81649913. Background: Percutaneous coronary interventions in patients with DM are associated with a higher incidence of death, restenosis, and stent thrombosis as compared to non-diabetic patients. The use of a DES has been shown to improve outcomes in diabetic patients. Methods: Out of 3,067 patients, enrolled in 126 centers worldwide in the NOBORI 2 registry, 888 patients suffered from DM, 213 of them (14% being insulin-dependent DM (IDDM. Two years’ follow-up has been completed in this study. Results: At 1- and 2-year follow-up, 97% and 95% of the patients, respectively, were available. The reported target lesion failure (TLF rates at 1- and 2-year follow-up were 6.0% and 7.2% in the DM group, respectively, and 3.0% and 4.2% in the non-DM group, respectively (P<0.001 for both years. Inside the DM group, the TLF rates of 9.9% and 11.7% at the 1- and 2-year follow-ups, respectively, in patients with IDDM were significantly higher than the TLF rates of 4

  14. Encapsulation, solid-phases identification and leaching of toxic metals in cement systems modified by natural biodegradable polymers.

    Science.gov (United States)

    Lasheras-Zubiate, M; Navarro-Blasco, I; Fernández, J M; Alvarez, J I

    2012-09-30

    Cement mortars loaded with Cr, Pb and Zn were modified by polymeric admixtures [chitosans with low (LMWCH), medium (MMWCH) and high (HMWCH) molecular weight and hydroxypropylchitosan (HPCH)]. The influence of the simultaneous presence of the heavy metal and the polymeric additive on the fresh properties (consistency, water retention and setting time) and on the compressive strength of the mortars was assessed. Leaching patterns as well as properties of the cement mortars were related to the heavy metals-bearing solid phases. Chitosan admixtures lessened the effect of the addition of Cr and Pb on the setting time. In all instances, chitosans improved the compressive strength of the Zn-bearing mortars yielding values as high as 15 N mm(-2). A newly reported Zn phase, dietrichite (ZnAl(2)(SO(4))(4)·22H(2)O) was identified under the presence of LMWCH: it was responsible for an improvement by 24% in Zn retention. Lead-bearing silicates, such as plumalsite (Pb(4)Al(2)(SiO(3))(7)), were also identified by XRD confirming that Pb was mainly retained as a part of the silicate network after Ca ion exchange. Also, the presence of polymer induced the appearance and stabilization of some Pb(IV) species. Finally, diverse chromate species were identified and related to the larger leaching values of Cr(VI). Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Antifungal activity of nano and micro charcoal particle polymers against Paecilomyces variotii, Trichoderma virens and Chaetomium globosum.

    Science.gov (United States)

    Yang, Hee Jin; Cha, Yun Jeong; Kim, Hern; Choi, Shin Sik

    2016-01-25

    This study investigates the antifungal activity of a polymer integrated with nano-porous charcoal particles against Paecilomyces variotii, Chaetomium globosum, Trichoderma virens, which are all filamentous fungi. The charcoal polymers were prepared by combining charcoal powders with plastic resin under a vacuum to form charcoal particle protrusions on the polymer surface. The mycelial growth of P. variotii and T. virens exhibited a reduction of 10 and 30%, respectively, after the conidia were pre-treated with charcoal polymers, and in particular, no mycelial growth was found in C. globosum during 5 days of culture. The adsorption of Ca(2+) into charcoal was suggested to inhibit growth due to the reduction in the flux of calcium ions (Ca(2+)) into the hyphae. In 5 h, about 15 mM of Ca(2+) were removed from CaCl2 solution with 0.2 g/mL of polymers, and the nano-sized pores of the charcoals on the polymer were responsible for the Ca(2+) adsorption. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Biodegradable versus durable polymer drug eluting stents in coronary artery disease: insights from a meta-analysis of 5,834 patients.

    Science.gov (United States)

    Lupi, Alessandro; Rognoni, Andrea; Secco, Gioel Gabrio; Lazzero, Maurizio; Nardi, Federico; Fattori, Rossella; Bongo, Angelo Sante; Agostoni, Pierfrancesco; Sheiban, Imad

    2014-04-01

    Biodegradable polymer drug eluting stents (BP-DES) have been developed to overcome the limitations of first generation durable polymer DES (DP-DES) but the clinical results of different BP-DES are not consistent. We performed a meta-analysis to compare the outcomes of BP-DES and DP-DES in the treatment of coronary artery disease (CAD). Online databases including MEDLINE were searched for studies comparing BP-DES and DP-DES for obstructive CAD that reported rates for overall mortality, myocardial infarction (MI), late stent thrombosis (LST), target lesion revascularization (TLR) and late lumen loss (LLL) with a follow-up of ≥ 6 months. Ten studies (5834 patients) with a 1-year median follow-up were included in the meta-analysis. When comparing patients treated with DP-DES and BP-DES those treated with BP-DES had lower LLL (in-stent: weighted mean difference (WMD) -0.10 mm, 95% CI = -0.17 to -0.03 mm, p = 0.004; in-segment: WMD -0.06 mm, 95% CI = -0.10 to -0.01 mm, p = 0.01) with lower TLR rates (OR 0.67, 95% CI = 0.47 to 0.98, p = 0.04). However, BP-DES did not improve mortality (OR 0.97, 95% CI = 0.73 to 1.29, p = 0.83), MI (OR 1.13, 95% CI = 0.87 to 1.46, p = 0.36) or LST rates (OR 0.64, 95% CI = 0.36 to 1.16, p = 0.14). A pre-specified subgroup analysis of Biolimus BP-DES confirmed significant LLL reduction without differences in other clinical endpoints. Meta-regression analysis demonstrated a strong significant inverse correlation between LLL and reference coronary diameter (p meta-analysis showed that BP-DES when compared with DP-DES significantly reduced LLL and TVR but without clear benefits on mortality, MI and LST rates. (Clinicaltrials.gov identifier: NCT01466634).

  17. Effect of electron beam irradiation on the enzymatic degradation of composites based on biodegradable polymers and coconut fiber

    Energy Technology Data Exchange (ETDEWEB)

    Kodama, Yasko; Bardi, Marcelo Augusto Goncalves; Machado, Luci Diva Brocardo, E-mail: ykodama@ipen.b, E-mail: marcelo.bardi@usp.b, E-mail: lmachado@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Rosa, Derval dos Santos, E-mail: derval.rosa@ufabc.edu.b [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil)

    2011-07-01

    The development of polymeric materials that are susceptible to microbiological degradation and that have properties similar to the conventional polymers would reduce waste deposit. Degradable plastics suffer significant change on chemical structure when submitted to specific environmental condition. PCL and PLLA have been extensively investigated due to their bio-assimilation and because they are considered as eco-friendly. So the degradation of PCL and PLLA homopolymers, PCL:PLLA 20:80 (w:w) blend and coconut fiber-modified composites were studied by means of their degradation under lipase enzyme from Pseudomonas cepacia. Non-irradiated and EB-irradiated samples at 50 kGy and 100 kGy were exposed during 24, 72, 120 and 168 hours to the enzyme-buffer solution and the retained mass of dried samples was accompanied over time. The results were compared to the not submitted to the enzyme solution samples. Degradation rate of PCL was higher than PLLA in the presence of Pseudomonas lipase. PLLA presence reduced PCL's enzymatic degradation in the PCL:PLLA 20:80 w:w blend. After 120 h exposure, blend mass loss variation approached pure PLLA behavior. Composites degradation behavior through time was similar to the blend. Values of retained mass for composites were superior to the blends suggesting that coconut fiber did not significantly degrade in the period of test. Degradation rate of 50 kGy-irradiated PCL slightly reduced, and it was observed increase of degradation rate of samples irradiated with 100 kGy, probably attributed to its crystallinity decrease. Degradation rate of irradiated composite was similar to the blend, suggesting that fiber presence did not affect significantly this parameter. Samples tested during 168 h were affected by the water absorption by PLLA or coconut fibers through time testing. Studied samples degraded accentuatedly in the enzyme presence and were not negatively affected by the radiation processing. (author)

  18. Effect of electron beam irradiation on the enzymatic degradation of composites based on biodegradable polymers and coconut fiber

    International Nuclear Information System (INIS)

    Kodama, Yasko; Bardi, Marcelo Augusto Goncalves; Machado, Luci Diva Brocardo; Rosa, Derval dos Santos

    2011-01-01

    The development of polymeric materials that are susceptible to microbiological degradation and that have properties similar to the conventional polymers would reduce waste deposit. Degradable plastics suffer significant change on chemical structure when submitted to specific environmental condition. PCL and PLLA have been extensively investigated due to their bio-assimilation and because they are considered as eco-friendly. So the degradation of PCL and PLLA homopolymers, PCL:PLLA 20:80 (w:w) blend and coconut fiber-modified composites were studied by means of their degradation under lipase enzyme from Pseudomonas cepacia. Non-irradiated and EB-irradiated samples at 50 kGy and 100 kGy were exposed during 24, 72, 120 and 168 hours to the enzyme-buffer solution and the retained mass of dried samples was accompanied over time. The results were compared to the not submitted to the enzyme solution samples. Degradation rate of PCL was higher than PLLA in the presence of Pseudomonas lipase. PLLA presence reduced PCL's enzymatic degradation in the PCL:PLLA 20:80 w:w blend. After 120 h exposure, blend mass loss variation approached pure PLLA behavior. Composites degradation behavior through time was similar to the blend. Values of retained mass for composites were superior to the blends suggesting that coconut fiber did not significantly degrade in the period of test. Degradation rate of 50 kGy-irradiated PCL slightly reduced, and it was observed increase of degradation rate of samples irradiated with 100 kGy, probably attributed to its crystallinity decrease. Degradation rate of irradiated composite was similar to the blend, suggesting that fiber presence did not affect significantly this parameter. Samples tested during 168 h were affected by the water absorption by PLLA or coconut fibers through time testing. Studied samples degraded accentuatedly in the enzyme presence and were not negatively affected by the radiation processing. (author)

  19. Adverse cardiovascular events associated with biodegradable polymer drug-eluting stents and durable polymer everolimus-eluting stents: A systematic review and meta-analysis of 10 randomized controlled trials.

    Science.gov (United States)

    Bundhun, Pravesh Kumar; Janoo, Girish; Yanamala, Chandra Mouli; Huang, Feng

    2017-07-01

    Controversies have been observed among network meta-analyses comparing biodegradable polymer drug-eluting stents (BP-DES) with durable polymer drug-eluting stents (DP-DES). We aimed to compare the adverse cardiovascular events associated with BP-DES and durable polymer everolimus-eluting stents (DP-EES) using a large number of patients obtained from randomized controlled trials (RCTs). Electronic databases were searched for randomized trials comparing BP-DES with DP-EES. Adverse cardiovascular outcomes observed between 6 months and 3 years were considered as the clinical endpoints in this analysis. Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated and the pooled analyses were performed with RevMan 5.3 software. All authors had full access to the data, and they have read and agreed to the manuscript as written. Ten trials involving a total number of 13,218 patients (7451 patients treated by BP-DES and 5767 patients treated by DP-EES) were included. No significant difference was observed when analyzing mortality and myocardial infarction between BP-DES and DP-EES with OR 1.08, 95% CI 0.87-1.34, P = .47 and OR 1.04, 95% CI 0.84-1.28, P = .72 respectively. Target vessel revascularization, target lesion revascularization, major adverse cardiac events, and stroke were also not significantly different with OR 1.11, 95% CI 0.92-1.33, P = .28; OR 1.11, 95% CI 0.94-1.33, P = .22; OR 1.12, 95% CI 0.99-1.27; P = .07; and OR 1.13, 95% CI 0.69-1.84; P = .62 respectively. In addition, total stent thrombosis (ST) was similarly reported between BP-DES and DP-EES with OR 0.85, 95% CI 0.59-1.21; P = .37. However, even if BP-DES were associated with a higher rate of definite ST with OR 1.69, 95% CI 0.92-3.08, P = .09 and DP-EES were associated with a higher rate of probable ST with OR 0.67, 95% CI 0.38-1.17, P = .16, these results were not statistically significant. Between 6 months and 3 years, BP-DES were similar in terms of

  20. Biodegradation of dodecylbenzene solfonate sodium by ...

    African Journals Online (AJOL)

    STORAGESEVER

    2010-01-04

    Jan 4, 2010 ... Key words: Branched anionic surfactants, biofilm, biodegradation, silanization. ... polymers, pesticides, oil recovery, textiles and paper ... surfactants are not degraded by microorganisms in the environment. Because of its low biodegradation ability and toxic effects on environment, BAS was forbidden in.

  1. Preparation and characterization of biodegradable poly(vinyl alcohol)

    African Journals Online (AJOL)

    Preparation and characterization of biodegradable poly(vinyl alcohol)/starch blends. ... Their mechanical properties, biodegradability and surface morphology were estimated and studied. The poly(vinyl alcohol)/starch blends show good ... Keywords: Starch, Acetylation, Biodegradation, Poly(vinyl alcohol), Polymer blend.

  2. The use of dielectric spectroscopy in the investigation of the effect of polymer choice on the flocculation of polystyrene particles

    DEFF Research Database (Denmark)

    Christensen, Peter Vittrup; Hinge, Mogens; Keiding, Kristian

    2009-01-01

    that the relaxation time of the dielectric dispersion increased as particle flocculation was initiated. Reduction of particle charge due to polymer addition was found to reduce the magnitude of the dielectric dispersion, whereas the formation of aggregates increased it. This resulted in decreasing magnitude when......The flocculation of colloidal suspensions using synthetic polymeric flocculants is an important operation in separation processes. Optimizing flocculant use requires insight into the underlying mechanisms governing flocculation. As most existing methods for the online characterization...... of flocculation processes can only be used on dilute suspensions, new methods applicable at high solid content levels are of interest. This study used dielectric spectroscopy to investigate the mechanisms involved in the flocculation of polystyrene particles with three different cationic polymers. We observed...

  3. Application of X-ray microtomography for the characterisation of hollow polymer-stabilised spray dried amorphous dispersion particles.

    Science.gov (United States)

    Gamble, John F; Terada, Masako; Holzner, Christian; Lavery, Leah; Nicholson, Sarah J; Timmins, Peter; Tobyn, Mike

    2016-08-20

    The aim of this study was to investigate the capability of X-ray microtomography to obtain information relating to powder characteristics such as wall thickness and solid volume fraction for hollow, polymer-stabilised spray dried dispersion (SDD) particles. SDDs of varying particle properties, with respect to shell wall thickness and degree of particle collapse, were utilised to assess the capability of the approach. The results demonstrate that the approach can provide insight into the morphological characteristics of these hollow particles, and thereby a means to understand/predict the processability and performance characteristics of the bulk material. Quantitative assessments of particle wall thickness, particle/void volume and thereby solid volume fraction were also demonstrated to be achievable. The analysis was also shown to be able to qualitatively assess the impact of the drying rate on the morphological nature of the particle surfaces, thus providing further insight into the final particle shape. The approach demonstrated a practical means to access potentially important particle characteristics for SDD materials which, in addition to the standard bulk powder measurements such as particle size and bulk density, may enable a better understanding of such materials, and their impact on downstream processability and dosage form performance. Crown Copyright © 2016. Published by Elsevier B.V. All rights reserved.

  4. Biodegradable elastomers for biomedical applications and regenerative medicine

    NARCIS (Netherlands)

    Bat, E.; Zhang Zheng, Z.Z.; Feijen, Jan; Grijpma, Dirk W.; Poot, Andreas A.

    2014-01-01

    Synthetic biodegradable polymers are of great value for the preparation of implants that are required to reside only temporarily in the body. The use of biodegradable polymers obviates the need for a second surgery to remove the implant, which is the case when a nondegradable implant is used. After

  5. Biodegradable elastomers for biomedical applications and regenerative medicine

    NARCIS (Netherlands)

    Bat, Erhan; Zhang, Zheng; Feijen, Jan; Grijpma, Dirk W.; Poot, Andre A.

    Synthetic biodegradable polymers are of great value for the preparation of implants that are required to reside only temporarily in the body. The use of biodegradable polymers obviates the need for a second surgery to remove the implant, which is the case when a nondegradable implant is used. After

  6. Lateral structuring and stability phenomena induced by block copolymers and core-shell nanogel particles at immiscible polymer/polymer interfaces

    Science.gov (United States)

    Gozen, Arif Omer

    We have investigated the parameters such as copolymer/nanoparticle concentration, architecture and molecular weight combined with film thickness, time and temperature in order to develop a molecular-level insight on how lateral interfacial structuring occurs at immiscible polymer/polymer interfaces. I order to develop a molecular-level understanding of how these 'smart' self-assembling materials and core-shell nanogel particles interact both intra- and inter-molecularly and form ordered structures in bulk, as well as at immiscible interfaces, we first focused on the response of core-shell polymer nanoparticles, designated CSNGs, composed of a cross-linked divinylbenzene core and poly(methyl methacrylate) (PMMA) arms as they segregate from PMMA homopolymer. We have demonstrated that these nanogel particles exhibit autophobic character when dispersed in high molecular weight homopolymer matrices and segregate to the interface with another fluid. We have further explored the migration of these new-generation nanogel particles (CSNG-Rs) segregating from PS homopolymer to PS/PMMA interfaces. Unlike the instability patterns observed with the CSNGs, which exhibit classical nucleation and growth mechanism with circular hole formation, we have observed an intriguing dewetting pattern and CSNG-Rs forming lateral aggregates and tentacle-like structures at the interface. In parallel with our core-shell particle studies, we have also explored the structuring of copolymer molecules that are far from equilibrium in bulk and complex laminate of polymer thin films. Our early triblock copolymer studies have proven that molecular asymmetry has a profound effect on order-disorder transition temperature. We focused primarily on the effect of the copolymer chemical composition (i.e., block sizes) on the dewetting behavior of PS/SM thin films on PMMA. We elucidate the interfacial segregation and concurrent micellization of diblock copolymers in a dynamically evolving environment with

  7. Vascular response to percutaneous coronary intervention with biodegradable-polymer vs. new-generation durable-polymer drug-eluting stents: a meta-analysis of optical coherence tomography imaging trials.

    Science.gov (United States)

    Cassese, Salvatore; Xhepa, Erion; Ndrepepa, Gjin; Kufner, Sebastian; Colleran, Roisin; Giacoppo, Daniele; Koppara, Tobias; Mankerious, Nader; Byrne, Robert A; Laugwitz, Karl-Ludwig; Schunkert, Heribert; Fusaro, Massimiliano; Kastrati, Adnan; Joner, Michael

    2018-01-02

    Whether biodegradable-polymer drug-eluting stents (BP-DES) induce a vascular response at follow-up more favourable than that of new-generation durable-polymer drug-eluting stents (DP-DES) remains controversial. We sought to evaluate the vascular response to percutaneous coronary intervention (PCI) with BP-DES vs. new-generation DP-DES as assessed by optical coherence tomography (OCT) imaging at follow-up. We undertook a meta-analysis of aggregate data by searching electronic scientific databases for investigations of PCI-patients receiving BP-DES vs. new-generation DP-DES and OCT imaging at follow-up. The primary outcome was neointima hyperplasia (NIH) thickness. The co-primary outcome was the incidence of lesions with uncovered struts. The main secondary outcome was the incidence of lesions with malapposed struts. Among 10 trials, a total of 544 PCI-patients were assigned to BP-DES (n = 282) or new-generation DP-DES (n = 262). Of these, 447 participants with 480 treated lesions had analysable OCT imaging at a weighted median follow-up of 7 months. Lesions treated with BP-DES vs. new-generation DP-DES showed comparable NIH thickness [weighted mean difference 95% confidence intervals (CI)  = -11.37 (-29.25, 6.52); P = 0.21]. However, thick-struts (>100 μm) BP-DES showed less NIH thickness as compared to new-generation DP-DES [-20.39 (-33.83, -6.95); P = 0.003]. BP-DES vs. new-generation DP-DES showed a higher risk for uncovered struts [odds ratio 95% CI = 3.50 (1.69-7.26); P = 0.0008] and a trend towards higher risk for malapposed struts [2.01 (0.98-4.12); P = 0.06]. In PCI-patients with available OCT imaging at follow-up, BP-DES with thicker backbones delay vascular response as compared with new-generation DP-DES. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2018. For permissions, please email: journals.permissions@oup.com.

  8. Nano- and Micro-sized Molecularly Imprinted Polymer Particles on Solid Surfaces

    OpenAIRE

    Kamra, Tripta

    2015-01-01

    Molecularly imprinted polymers (MIPs) are artificial receptors made by imprinting template molecules in a polymer matrix followed by their removal through washing to obtain a specific and selective template cavities. This property of the MIPs have made them a very efficient material for diverse applications such as chromatography, purification, drug sensing, etc. Recently, zero-dimensional polymer materials, in the present case molecularly imprinted polymer nanoparticles (MIP nanoparticles), ...

  9. Impact of particle size on interaction forces between ettringite and dispersing comb-polymers in various electrolyte solutions.

    Science.gov (United States)

    Ferrari, Lucia; Kaufmann, Josef; Winnefeld, Frank; Plank, Johann

    2014-04-01

    The inter-particle forces play a fundamental role for the flow properties of a particle suspension in response to shear stresses. In concrete applications, cement admixtures based on comb-polymers like polycarboxylate-ether-based superplasticizer (PCE) are used to control the rheological behavior of the fresh mixtures, as it is negatively impacted by certain early hydration products, like the mineral ettringite. In this work, dispersion forces due to PCE were measured directly at the surface of ettringite crystals in different electrolyte solutions by the means of atomic force microscopy (AFM) applying spherical and sharp silicon dioxide tips. Results show an effective repulsion between ettringite surface and AFM tips for solutions above the IEP of ettringite (pH∼12) and significant attraction in solution at lower pH. The addition of polyelectrolytes in solution provides dispersion forces exclusively between the sharp tips (radius ≈ 10 nm) and the ettringite surface, whereas the polymer layer at the ettringite surface results to be unable to disperse large colloidal probes (radius ≈ 10 μm). A simple modeling of the inter-particle forces explains that, for large particles, the steric hindrance of the studied PCE molecules is not high enough to compensate for the Van der Waals and the attractive electrostatic contributions. Therefore, in cement suspensions the impact of ettringite on rheology is probably not only related to the particle charge, but also related to the involved particle sizes. Copyright © 2013 Elsevier Inc. All rights reserved.

  10. Modification of Polymer Network Properties through the Addition of Functional Nanogel Particles

    Science.gov (United States)

    Liu, JianCheng

    Multifunctional acrylic and methacrylic monomers have been widely applied in many photopolymerization applications to produce crosslinked polymers with advantages such as rapid curing, broad choices of commercially available monomers and desirable physical and mechanical properties. However, there still remain critical challenges for these materials during polymerization including limited conversion and early onset of gelation as well as the generation of significant polymerization shrinkage and stress. This thesis explores the effects of network property modification through the addition of polymeric nanoparticles or nanogels. In order to understand the relationship between nanogel structure and composite material properties, nanogels with different architectures and functionalities were studied during polymerization in terms of kinetics, shrinkage and stress reduction, mechanical performance and reaction mechanisms. Nanogel composite formulations were evaluated to understand the interaction between nanogel structure with the resin matrix during polymerization through adjustment of nanogel branching densities and reactivity of polymer chain ends. It was found that both the chemical crosslinking from reactive chain ends and physical entanglements of high branching density nanogels with the resin matrix dramatically could improve final material mechanical strength. The reductions in overall volumetric shrinkage and shrinkage stress were found to follow at least proportional behavior with respect to nanogel loading concentration while maintaining similar final conversion and modulus results compared with the control resin. Nanogels containing unique functionalities were designed in order to modify reaction mechanism during secondary polymerization. A nanogel containing an integrated photoinitiator and active chain-end RAFT groups was able to initiate secondary polymerization from the nanogel phase so that localized polymerization was achieved from the beginning of

  11. Polymer composite adsorbents using particles of molecularly imprinted polymers or aluminium oxide nanoparticles for treatment of arsenic contaminated waters.

    Science.gov (United States)

    Önnby, L; Pakade, V; Mattiasson, B; Kirsebom, H

    2012-09-01

    Removal of As(V) by adsorption from water solutions was studied using three different synthetic adsorbents. The adsorbents, (a) aluminium nanoparticles (Alu-NPs, polymers (polymer backbones of pure polyacrylamide (MIP-cryo) were of better stability than the amine containing polymer backbone (Alu-cryo). Both composites worked well in the studied pH range of pH 2-8. Adsorption tested in real wastewater spiked with arsenic showed that co-ions (nitrate, sulphate and phosphate) affected arsenic removal for Alu-cryo more than for MIP-cryo. Both composites still adsorbed well in the presence of counter-ions (copper and zinc) present at low concentrations (μg/l). The unchanged and selective adsorption in realistic water observed for MIP-cryo was concluded to be due to a successful imprinting, here controlled using a non-imprinted polymer (NIP). A development of MIP-cryo is needed, considering its low adsorption capacity. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Current knowledge on biodegradable microspheres in drug delivery.

    Science.gov (United States)

    Prajapati, Vipul D; Jani, Girish K; Kapadia, Jinita R

    2015-08-01

    Biodegradable microspheres have gained popularity for delivering a wide variety of molecules via various routes. These types of products have been prepared using various natural and synthetic biodegradable polymers through suitable techniques for desired delivery of various challenging molecules. Selection of biodegradable polymers and technique play a key role in desired drug delivery. This review describes an overview of the fundamental knowledge and status of biodegradable microspheres in effective delivery of various molecules via desired routes with consideration of outlines of various compendial and non-compendial biodegradable polymers, formulation techniques and release mechanism of microspheres, patents and commercial biodegradable microspheres. There are various advantages of using biodegradable polymers including promise of development with different types of molecules. Biocompatibility, low dosage and reduced side effects are some reasons why usage biodegradable microspheres have gained in popularity. Selection of biodegradable polymers and formulation techniques to create microspheres is the biggest challenge in research. In the near future, biodegradable microspheres will become the eco-friendly product for drug delivery of various genes, hormones, proteins and peptides at specific site of body for desired periods of time.

  13. Universal shape characteristics for the mesoscopic polymer chain via dissipative particle dynamics.

    Science.gov (United States)

    Kalyuzhnyi, O; Ilnytskyi, J M; Holovatch, Yu; von Ferber, C

    2016-12-21

    In this paper we study the shape characteristics of a polymer chain in a good solvent using a mesoscopic level of modelling. The dissipative particle dynamics simulations are performed in 3D space at a range of chain lengths N. The scaling laws for the end-to-end distance and gyration radius are examined first and found to hold for [Formula: see text] yielding a reasonably accurate value for the Flory exponent ν. Within the same interval of chain lengths, the asphericity, prolateness and some other shape characteristics of the chain are found to become independent of N. Their mean values are found to agree reasonably well with the respective theoretical results and lattice Monte Carlo (MC) simulations. We found the probability distribution for a wide range of shape characteristics. For the asphericity and prolateness they are quite broad, resembling in form the results of lattice MC simulations. By means of the analytic fitting of these distributions, the most probable values for the shape characteristics are found to supplement their mean values.

  14. Refractive Index Tuning of Hybrid Materials for Highly Transmissive Luminescent Lanthanide Particle-Polymer Composites.

    Science.gov (United States)

    Kim, Paul; Li, Cheng; Riman, Richard E; Watkins, James

    2018-03-14

    High-refractive-index ZrO 2 nanoparticles were used to tailor the refractive index of a polymer matrix to match that of luminescent lanthanide-ion-doped (La 0.92 Yb 0.075 Er 0.005 F 3 ) light-emitting particles, thereby reducing scattering losses to yield highly transparent emissive composites. Photopolymerization of blends of an amine-modified poly(ether acrylate) oligomer and tailored quantities of ZrO 2 nanoparticles yielded optically transparent composites with tailored refractive indices between 1.49 and 1.69. By matching the refractive index of the matrix to that of La 0.92 Yb 0.075 Er 0.005 F 3 , composites with high transmittance (>85%) and low haze from the visible to infrared regions, bright 1530 nm optical emissions were achieved at solids loadings of La 0.92 Yb 0.075 Er 0.005 F 3 , ranging from 5 to 30 vol %. These optical results suggest that a hybrid matrix approach is a versatile strategy for the fabrication of functional luminescent optical composites of high transparency.

  15. Computational analysis of particle reinforced viscoelastic polymer nanocomposites - statistical study of representative volume element

    Science.gov (United States)

    Hu, Anqi; Li, Xiaolin; Ajdari, Amin; Jiang, Bing; Burkhart, Craig; Chen, Wei; Brinson, L. Catherine

    2018-05-01

    The concept of representative volume element (RVE) is widely used to determine the effective material properties of random heterogeneous materials. In the present work, the RVE is investigated for the viscoelastic response of particle-reinforced polymer nanocomposites in the frequency domain. The smallest RVE size and the minimum number of realizations at a given volume size for both structural and mechanical properties are determined for a given precision using the concept of margin of error. It is concluded that using the mean of many realizations of a small RVE instead of a single large RVE can retain the desired precision of a result with much lower computational cost (up to three orders of magnitude reduced computation time) for the property of interest. Both the smallest RVE size and the minimum number of realizations for a microstructure with higher volume fraction (VF) are larger compared to those of one with lower VF at the same desired precision. Similarly, a clustered structure is shown to require a larger minimum RVE size as well as a larger number of realizations at a given volume size compared to the well-dispersed microstructures.

  16. Synthesis of Barium Titanate (BT) Nano Particles via Hydrothermal Route for the Production of BT-Polymer Nanocomposite

    Science.gov (United States)

    Habib, A.; Haubner, R.; Jakopic, G.; Stelzer, N.

    2007-08-01

    Barium titanate (high-k dielectric material) nano-powders (approx. 30 nm to 60 nm) were synthesised using hydrothermal route under moderate conditions. Effect of temperature and time was studied using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction techniques. Obtained barium titanate nano-powders were dispersed in thermoplastic polymethyl methacrylate (PMMA) to get homogeneous dispersions. Thin layers were obtained using these dispersions to achieve BaTiO3 endorsed polymer layers by dip-coating for improved polymer insulators on various substrates e.g., glass, and Au sputtered silicon wafers. SEM and focused ion beam (FIB) techniques were used to study the dispersion of barium titanate nano-particles in PMMA. The layers obtained showed homogenous distribution of BaTiO3 nano particles with no agglomeration.

  17. Amperometric detection of morphine based on poly(3,4-ethylenedioxythiophene) immobilized molecularly imprinted polymer particles prepared by precipitation polymerization

    International Nuclear Information System (INIS)

    Ho, K.-C.; Yeh, W.-M.; Tung, T.-S.; Liao, J.-Y.

    2005-01-01

    Molecular imprinting is a novel technique used for chiral separation, artificial antibodies, sensors, and assays. Typically, molecular imprinted polymers (MIPs) are monoliths with irregular shapes. However, microspherical shapes with more uniform size can be obtained by the method of precipitation polymerization, which offers a higher active surface area by manipulating its compositions. In this study, MIP particles for the target molecule, morphine, were synthesized using a precipitation polymerization method that is more facile than the previous one that produced a thermally polymerized bulk. The conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), was utilized to immobilize the MIP particles onto the indium tin oxide (ITO) glass as a MIP/PEDOT-modified electrode. The sensitivity for the MIP/PEDOT-modified electrode with MIP particles was 41.63 μA/cm 2 mM, which is more sensitive than that with non-MIP particles or that of a single PEDOT film with no incorporated particles in detecting morphine ranging from 0.1 to 2 mM. The detection limit was 0.3 mM (S/N = 3). In addition, we presented that the modified electrode can discriminate codeine that plays an interfering species

  18. Controlled Dissolution of Griseofulvin Solid Dispersions from Electrosprayed Enteric Polymer Micromatrix Particles: Physicochemical Characterization and in Vitro Evaluation.

    Science.gov (United States)

    Roine, Jorma; Kaasalainen, Martti; Peurla, Markus; Correia, Alexandra; Araújo, Francisca; Santos, Hélder A; Murtomaa, Matti; Salonen, Jarno

    2015-07-06

    The oral bioavailability of a poorly water-soluble drug is often inadequate for the desired therapeutic effect. The bioavailability can be improved by enhancing the physicochemical properties of the drug (e.g., dissolution rate, permeation across the gastrointestinal tract). Other approach include shielding the drug from the gastric metabolism and targeted drug release to obtain optimal drug absorption. In this study, a poorly water-soluble model drug, griseofulvin, was encapsulated as disordered solid dispersions into Eudragit L 100-55 enteric polymer micromatrix particles, which were produced by electrospraying. Similar micromatrix particles were also produced with griseofulvin-loaded thermally oxidized mesoporous silicon (TOPSi) nanoparticles dispersed to the polymer micromatrices. The in vitro drug dissolution at pH 1.2 and 6.8, and permeation at pH 7.4 across Caco-2/HT29 cell monolayers from the micromatrix particles, were investigated. The micromatrix particles were found to be gastro-resistant, while at pH 6.8 the griseofulvin was released very rapidly in a fast-dissolving form. Compared to free griseofulvin, the permeability of encapsulated griseofulvin across the intestinal cell monolayers was greatly improved, particularly for the TOPSi-doped micromatrix particles. The griseofulvin solid dispersions were stable during storage for 6 months at accelerated conditions. Overall, the method developed here could prove to be a useful oral drug delivery solution for improving the bioavailability of poorly water-soluble or otherwise problematic drugs.

  19. Mesoscale Simulation of Polymer Reaction Equilibrium: Combining Dissipative Particle Dynamics with Reaction Ensemble Monte Carlo. I. Polydispersed Polymer Systems

    Czech Academy of Sciences Publication Activity Database

    Lísal, Martin; Brennan, J.K.; Smith, W.R.

    2006-01-01

    Roč. 125, č. 16 (2006), s. 16490501-16490515 ISSN 0021-9606 R&D Projects: GA ČR(CZ) GA203/05/0725; GA AV ČR 1ET400720409; GA AV ČR 1ET400720507 Institutional research plan: CEZ:AV0Z40720504 Keywords : simulation * polymer Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.166, year: 2006

  20. Production of Polyhydroxyalkanoates, a bacterial biodegradable ...

    African Journals Online (AJOL)

    ... production has restricted its applications. The possibility of producing this polymer commercially and at comparable cost has been the main focus in this area. Key Words: Polyhydroxyalkanoates, biodegradable polymer, bioplastic, poly(3-hydroxybutyrate), biosynthesis. African Journal of Biotechnology Vol.3(1) 2004: 18- ...

  1. Biodegradable multifunctional oil production chemicals: Thermal polyaspartates

    International Nuclear Information System (INIS)

    Ross, R.J.; Ravenscroft, P.D.

    1996-01-01

    The paper deals with biodegradable oil production chemicals. Control of both mineral scale and corrosion with a single, environmentally acceptable material is an ambitious goal. Polyaspartate polymers represent a significant milestone in the attainment of this goal. Thermal polyaspartates (TPA) are polycarboxylate polymers derived via thermal condensation of the naturally occurring amino acid aspartic acid. These protein-like polymers are highly biodegradable and non-toxic, and are produced by an environmentally benign manufacturing process. TPAs exhibit excellent mineral scale inhibition activity and CO 2 corrosion control. Laboratory data on scale inhibition and corrosion control in the North Sea oil field production applications is presented. 8 refs., 2 figs., 6 tabs

  2. Heat Dissipation of Resonant Absorption in Metal Nanoparticle-Polymer Films Described at Particle Separation Near Resonant Wavelength

    Directory of Open Access Journals (Sweden)

    Jeremy R. Dunklin

    2017-01-01

    Full Text Available Polymer films containing plasmonic nanostructures are of increasing interest for development of responsive energy, sensing, and therapeutic systems. The present work evaluates heat dissipated from power absorbed by resonant gold (Au nanoparticles (NP with negligible Rayleigh scattering cross sections randomly dispersed in polydimethylsiloxane (PDMS films. Finite element analysis (FEA of heat transport was coordinated with characterization of resonant absorption by Mie theory and coupled dipole approximation (CDA. At AuNP particle separation greater than resonant wavelength, correspondence was observed between measured and CDA-predicted optical absorption and FEA-derived power dissipation. At AuNP particle separation less than resonant wavelength, measured extinction increased relative to predicted values, while FEA-derived power dissipation remained comparable to CDA-predicted power absorption before lagging observed extinguished power at higher AuNP content and resulting particle separation. Effects of isolated particles, for example, scattering, and particle-particle interactions, for example, multiple scattering, aggregation on observed optothermal activity were evaluated. These complementary approaches to distinguish contributions to resonant heat dissipation from isolated particle absorption and interparticle interactions support design and adaptive control of thermoplasmonic materials for a variety of implementations.

  3. Microbial Enzymatic Degradation of Biodegradable Plastics.

    Science.gov (United States)

    Roohi; Bano, Kulsoom; Kuddus, Mohammed; Zaheer, Mohammed R; Zia, Qamar; Khan, Mohammed F; Ashraf, Ghulam Md; Gupta, Anamika; Aliev, Gjumrakch

    2017-01-01

    The renewable feedstock derived biodegradable plastics are important in various industries such as packaging, agricultural, paper coating, garbage bags and biomedical implants. The increasing water and waste pollution due to the available decomposition methods of plastic degradation have led to the emergence of biodegradable plastics and biological degradation with microbial (bacteria and fungi) extracellular enzymes. The microbes utilize biodegradable polymers as the substrate under starvation and in unavailability of microbial nutrients. Microbial enzymatic degradation is suitable from bioremediation point of view as no waste accumulation occurs. It is important to understand the microbial interaction and mechanism involved in the enzymatic degradation of biodegradable plastics under the influence of several environmental factors such as applied pH, thermo-stability, substrate molecular weight and/or complexity. To study the surface erosion of polymer film is another approach for hydrolytic degradation characteristion. The degradation of biopolymer is associated with the production of low molecular weight monomer and generation of carbon dioxide, methane and water molecule. This review reported the degradation study of various existing biodegradable plastics along with the potent degrading microbes (bacteria and fungi). Patents available on plastic biodegradation with biotechnological significance is also summarized in this paper. This paper assesses that new disposal technique should be adopted for the degradation of polymers and further research is required for the economical production of biodegradable plastics along with their enzymatic degradation. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  4. Comb polymer architecture and particle size effects on the behavior of biphasic nanoparticle inks for direct-write assembly

    Science.gov (United States)

    Yoshikawa, Jun

    Biphasic nanoparticle mixtures composed of attractive and repulsive colloidal species enable the direct-write assembly of 3D structures with much finer features than those produced by pure colloidal gels. These mixtures rely on the use of comb polymer dispersants to render one particle population stable, while the other population is attractive. In this thesis, we systematically investigate the effects of comb polymer architecture and particle size ratio on the behavior of biphasic nanoparticle inks with the overarching aim of further advancing the direct-write assembly of 3D colloidal structures. We first investigated the effects of both pure polyelectrolytes, poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA), and comb polymer dispersants composed of a PMAA backbone with methoxy-poly(ethylene oxide) (mPEO) teeth of varying molecular weights on the stability of barium titanate (BaTiO 3) suspensions. While each dispersant imparts stability to BaTiO 3 nanoparticles at low ionic strength (teeth (MWteeth = 2000) provides stability at higher ionic strengths over a broad range of particle sizes and counterion valencies. These results provide guidelines for tailoring the molecular architecture and functionality of comb polymer dispersants for optimal stabilization of the repulsive particle population within the biphasic inks. Next, particle size effects on the rheological properties of biphasic nanoparticle suspensions are studied. Shear elastic modulus, shear yield stress, and compressive yield stress are measured for mixtures of varying total volume fraction, attractive-to-repulsive volume fraction, and particle size ratio between attractive and repulsive species. Our observations indicate that the repulsive particles hinder the formation of the attractive gel network. The time required for shear elastic modulus to approach a steady-state value increases with the fraction of repulsive species. Furthermore, this behavior becomes more significant with increasing

  5. Particle size effect of BaTiO3nanofillers on the energy storage performance of polymer nanocomposites.

    Science.gov (United States)

    Bi, Meihua; Hao, Yanan; Zhang, Jiameng; Lei, Ming; Bi, Ke

    2017-11-02

    Polymer nanocomposites are a promising substitute for energy-storage dielectric materials in pulsed power systems. A barium titanate/polyvinylidenefluoride (BT/PVDF) nanocomposite is one of the most widely studied composite systems due to its comprehensive excellent dielectric properties. As the dielectric response of nanocomposites depends strongly on the size of the fillers, in this study, BT/PVDF nanocomposites with 92.3 nm, 17.8 nm and 5.9 nm BT particle fillers are fabricated to reveal the particle size effect of the fillers on the energy storage performance of the polymer nanocomposites. Owing to the small particle size and good dispersibility of the nanofillers, the nanocomposites with smaller BT particles show more uniform and denser microstructures. Moreover, with the increase of the filler fraction, the dielectric results indicate a breakdown strength enhancement in the nanocomposites with sub-20 nm BT fillers, which is quite different from the nanocomposites with normal fillers, and therefore leads to superior energy storage performance. This study provides experimental evidence for the application of ultrafine nanofillers in the nanocomposite for future energy storage systems.

  6. Controllable dielectric and electrical performance of polymer composites with novel core/shell-structured conductive particles through biomimetic method

    International Nuclear Information System (INIS)

    Yang, Dan; Tian, Ming; Wang, Wencai; Li, Dongdong; Li, Runyuan; Liu, Haoliang; Zhang, Liqun

    2013-01-01

    Highlights: ► Conductive core/shell-structured particles were synthesized by biomimetic method. ► These particles with silica/poly(dopamine)/silver core and poly(dopamine) shell. ► Dielectric composites were prepared with resulted particles and silicone elastomer. ► The dielectric properties of the composites can be controlled by shell thickness. ► This biomimetic method is simple, nontoxic, efficient and easy to control. - Abstract: Novel silica/poly(dopamine)/silver (from inner to outer) (denoted as SiO 2 /PDA/Ag) conductive micro-particles were first synthesized by biomimetic poly(dopamine) coating. These micro-particles were then coated with a poly(dopamine) layer to form core/shell-structured particles, with silica/poly(dopamine)/silver core and poly(dopamine) shell (denoted as SiO 2 /PDA/Ag/PDA). This multilayer core/shell micro-particles were confirmed by scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and transmission electron microscope. Polymer composites were then prepared by mechanical blending of poly(dimethyl siloxane) and the core/shell-structured particles. It was found that the silver layer and the poly(dopamine) shell had good adhesion with substrate and they kept intact even under violent shearing stress during mechanical mixing. The effect of the thickness of outermost poly(dopamine) shell as well as the loading amount of this filler on the dielectric and electrical properties of the composites was further studied. The results showed that the dielectric constant, dielectric loss, and conductivity of the composites decreased with increasing shell thickness (10–53 nm) at the same loading level. And the maximal dielectric constant of composites was achieved in the composites filled with SiO 2 /PDA/Ag/PDA (with 10–15 nm PDA shell) particles, which was much larger than that of the composite filled with SiO 2 /PDA/Ag particles without insulative PDA shell. At the same time, the composites can change

  7. Role of organoclay in controlling the morphology and crystal-growth behavior of biodegradable polymer-blend thin films studied using atomic force microscopy

    CSIR Research Space (South Africa)

    Malwela, T

    2014-09-01

    Full Text Available This study reports the effect of organically modified nanoclay on the morphology and crystal growth behavior of biodegradable polylactide/poly[(butylene succinate)-co-adipate] (PLA/PBSA) blend thin films with the average thickness of 280 nm...

  8. Nanofibers extraction from palm mesocarp fiber for biodegradable polymers incorporation; Extracao de nanofibras a partir do mesocarpo do dende para incorporacao em polimeros biodegradsveis

    Energy Technology Data Exchange (ETDEWEB)

    Kuana, Vanessa A.; Rodrigues, Vanessa B.; Takahashi, Marcio C., E-mail: ayu.kuana@gmail.com [Universidade Federal de Sao Carlos (UFSCar), Sao Carlos, SP (Brazil); Campos, Adriana de; Sena Neto, Alfredo R.; Mattoso, Luiz H.C.; Marconcini, Jose M. [Embrapa Instrumentacao (EMBRAPA/CNPDIA), Sao Carlos, SP (Brazil)

    2015-07-01

    The palm mesocarp fibers are residues produced by the palm oil industries. The objective of this paper is to determine an efficient treatment to extract crystal cellulose nanofibers from the palm mesocarp fibers to be incorporated in biodegradable polymeric composites. The fibers were saponified, bleached and analyzed with thermal gravimetric analysis, X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. (author)

  9. Synthesis of tailored core-brush polymer particles via a living radical polymerization and architecture of colloidal crystals.

    Science.gov (United States)

    Ishizu, Koji; Amir, Isamu; Okamoto, Nobuyuki; Uchida, Satoshi; Ozawa, Masaaki; Chen, Hui

    2011-01-01

    Narrow disperse core-brush polymer nanoparticles (BP) were synthesized by grafting from photo-induced atom transfer radical polymerization (ATRP) of 2-hydroxyethyl methacrylate (HEMA) from N,N-diethyldithiocarbamate (DC) groups of core-shell particle surface. We constructed colloidal crystals of these particles by depositing on glass substrate. By variation of the particle size, the brilliant color could be varied throughout the visible spectrum. We locked also permanently such colloidal crystals by cross-linking of poly(2-hydroxyethyl methacrylate) (PHEMA) brush phases with glutaraldehyde. The peak wavelength (λ(max)) in the reflection spectra agreed well with the bandgap position for light incident on the (1 1 1) face of face-centered cubic (fcc) lattice according to Bragg's law. Copyright © 2010 Elsevier Inc. All rights reserved.

  10. Synthesis of Nanostructured/Macroscopic Low-Density Copper Foams Based on Metal-Coated Polymer Core-Shell Particles.

    Science.gov (United States)

    Kim, Sung Ho; Bazin, Nick; Shaw, Jessica I; Yoo, Jae-Hyuck; Worsley, Marcus A; Satcher, Joe H; Sain, John D; Kuntz, Joshua D; Kucheyev, Sergei O; Baumann, Theodore F; Hamza, Alex V

    2016-12-21

    A robust, millimeter-sized low-density Cu foam with ∼90% (v/v) porosity, ∼30 nm thick walls, and ∼1 μm diameter spherical pores is prepared by the slip-casting of metal-coated polymer core-shell particles followed by a thermal removal of the polymer. In this paper, we report our key findings that enable the development of the low-density Cu foams. First, we need to synthesize polystyrene (PS) particles coated with a very thin Cu layer (in the range of tens of nanometers). A simple reduction in the amount of Cu deposited onto the PS was not sufficient to form such a low-density Cu foams due to issues related to foam collapse and densification upon the subsequent polymer removal step. Precise control over the morphology of the Cu coating on the particles is essential for the synthesis of a lower density of foams. Second, improving the dispersion of PS-Cu particles in a suspension used for the casting as well as careful optimization of a baking condition minimize the formation of irregular large voids, leading to Cu foams with a more uniform packing and a better connectivity of neighboring Cu hollow shells. Finally, we analyzed mechanical properties of the Cu foams with a depth-sensing indentation test. The uniform Cu foams show a significant improvement in mechanical properties (∼1.5× modulus and ∼3× hardness) compared to those of uncontrolled foam samples with a similar foam density but irregular large voids. Higher surface areas and a good electric conductivity of the Cu foams present a great potential to future applications.

  11. Degradation of spacecraft polymer films by charged particle irradiation and its influences on charging/discharging events

    Science.gov (United States)

    Tahara, Hirokazu

    2003-09-01

    Influences of ion bombardment on chemical structures and negative charging/discharging characteristics of spacecraft polymer films were examined. Furthermore, arcing characteristics of negatively-biased anodized aluminum sample (AAS) plates in plasma environment were investigated. Polyimide Upilex-S and Teflon FEP films were exposed to oxygen and nitrogen ion beams. The in-situ x-ray photoelectron spectroscopy and quadrupole mass spectrometer analyses showed that an addition reaction and a desorption of structural components occurred by ion bombardment. After degradation of film surfaces by ion bombardment, negative charging experiment was carried out by electron beam exposure. The characteristic of the charging current by exposure of electron beams to polymer films showed a periodical time variation with a slow decay after a peak. The variation corresponded to a cyclic phenomenon of negative charging and discharging on the film surfaces. The cyclic period increased with dose of nitrogen ions had attacked. Degradation of polymer films by ion bombardment was considered to influence their charging/discharging phenomenon. The arcing characteristics for AAS in plasma environment showed that both the peak arc current and the total charge emitted by arcing increased with initial charging voltage and neutral particle number density. The diameter of arc spots increased with initial charging voltage although it was almost constant regardless of neutral particle density. Accordingly, high voltage operation of LEO spacecraft might bring degradation of AAS by arcing.

  12. Polímeros sintéticos biodegradáveis: matérias-primas e métodos de produção de micropartículas para uso em drug delivery e liberação controlada Biodegradable synthetic polymers: raw-materials and production methods of microparticles for drug delivery and controlled release

    Directory of Open Access Journals (Sweden)

    Patrícia Severino

    2011-01-01

    Full Text Available Micropartículas produzidas a partir de polímeros sintéticos têm sido amplamente utilizadas na área farmacêutica para encapsulação de princípios ativos. Essas micropartículas apresentam as vantagens de proteção do princípio ativo, mucoadesão e gastrorresistência, melhor biodisponibilidade e maior adesão do paciente ao tratamento. Além disso, utiliza menores quantidade de princípio ativo para obtenção do efeito terapêutico proporcionando diminuição dos efeitos adversos locais, sistêmicos e menor toxidade. Os polímeros sintéticos empregados na produção das micropartículas são classificados biodegradáveis ou não biodegradáveis, sendo os biodegradáveis mais utilizados por não necessitam ser removidos cirurgicamente após o término de sua ação. A produção das micropartículas poliméricas sintéticas para encapsulação tanto de ativos hidrofílicos quanto hidrofóbicos pode ser emulsificação por extração e/ou evaporação do solvente; coacervação; métodos mecânicos e estão revisados neste artigo evidenciando as vantagens, desvantagens e viabilidade de cada metodologia. A escolha da metodologia e do polímero sintético a serem empregados na produção desse sistema dependem da aplicação terapêutica requerida, bem como a simplicidade, reprodutibilidade e factibilidade do aumento de escala da produção.Microparticles produced from synthetic polymers have been widely used in the pharmaceutical field for encapsulation of drugs. These microparticles show several advantages such as drug protection, mucoadhesion, gastro-resistance, improved bioavailability and increased patient's compliance. In addition, it is possible to use lower amount of drug to achieve therapeutic efficiency with reduced local/systemic adverse side effects and low toxicity. Synthetic polymers used for the production of microparticles are classified as biodegradable or non-biodegradable, being the former more popular since these do

  13. Influences of process and formulation parameters on powder flow properties and immunogenicity of spray dried polymer particles entrapping recombinant pneumococcal surface protein A.

    Science.gov (United States)

    Anish, Chakkumkal; Upadhyay, Arun K; Sehgal, Devinder; Panda, Amulya Kumar

    2014-05-15

    Particle size, antigen load and its release characteristic are the three the main attributes of polymer particles based vaccine delivery systems. The present studies focus on the formulation of spray dried polylactide microparticles entrapping pneumococcal surface protein A (PspA). Influence of process variables during polymer particle formation were optimized by using half-factorial design. Feed rate and atomization pressure during spray drying were found to be the most important parameters for achieving uniform size particles. Spray drying of preformed particles from different stages of solvent evaporation method resulted in formation of particle having different porosity and protein release profile. Presence of polyvinyl alcohol in the external aqueous phase not only contributed towards regulating the size of particles but also influenced the burst release of protein from particles. Polymer particles entrapping PspA elicited robust IgG responses both in mice and in rats. Antigen load in microparticles correlated with the antibody titer indicating the maintenance of protein integrity during particle formation using spray drying. Both, process engineering and formulation parameters during spray drying influenced the particles in terms of size, load and antigen release characteristics. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Three-dimensional smoothed particle hydrodynamics simulation for injection molding flow of short fiber-reinforced polymer composites

    Science.gov (United States)

    He, Liping; Lu, Gang; Chen, Dachuan; Li, Wenjun; Lu, Chunsheng

    2017-07-01

    This paper investigates the three-dimensional (3D) injection molding flow of short fiber-reinforced polymer composites using a smoothed particle hydrodynamics (SPH) simulation method. The polymer melt was modeled as a power law fluid and the fibers were considered as rigid cylindrical bodies. The filling details and fiber orientation in the injection-molding process were studied. The results indicated that the SPH method could effectively predict the order of filling, fiber accumulation, and heterogeneous distribution of fibers. The SPH simulation also showed that fibers were mainly aligned to the flow direction in the skin layer and inclined to the flow direction in the core layer. Additionally, the fiber-orientation state in the simulation was quantitatively analyzed and found to be consistent with the results calculated by conventional tensor methods.

  15. Fabrication of shape-controllable polyaniline micro/nanostructures on organic polymer surfaces: obtaining spherical particles, wires, and ribbons.

    Science.gov (United States)

    Zhong, Wenbin; Wang, Yongxin; Yan, Yan; Sun, Yufeng; Deng, Jianping; Yang, Wantai

    2007-04-19

    A novel strategy was developed in order to prepare various micro/nanostructured polyanilines (PANI) on polymer substrates. The strategy involved two main steps, i.e., a grafting polymerization of acrylate acid (AA) onto the surface of a polypropylene (PP) film and subsequently an oxidative polymerization of aniline on the grafted surface. By tuning the conformation of the surface-grafted poly acrylate acid (PAA) brushes, as well as the ratio of AA to aniline, the shape of the PANIs fixated onto the surfaces of the polymer substrate could be controlled to go from spherical particles to nanowires and eventually to nanoribbons. In these structures, the PAA brushes not only acted as templates but also as dopants of PANI, and thereby, the nanostructured PANIs could be strongly bonded with the substrate. In addition, the surface of the PP films grafted with polyaniline nanowires and nanoribbons displayed superhydrophobicity with contact angles for water of approxiamtely 145 and 151 degrees , respectively.

  16. Switching and memory effects in composite films of semiconducting polymers with particles of graphene and graphene oxide

    Science.gov (United States)

    Krylov, P. S.; Berestennikov, A. S.; Aleshin, A. N.; Komolov, A. S.; Shcherbakov, I. P.; Petrov, V. N.; Trapeznikova, I. N.

    2015-08-01

    The effects of switching were investigated in composite films based on multifunctional polymers. i.e., derivatives of carbazole (PVK) and fluorene (PFD), as well as based on particles of graphene (Gr) and graphene oxide (GO). The concentration of Gr and GO particles in the PVK(PFD) matrix was varied in the range of 2-3 wt %, which corresponded to the percolation threshold in these systems. The atomic composition of the composite films PVK: GO was examined using X-ray photoelectron spectroscopy. It was found that the effect of switching in structures of the form Al/PVK(PFD): GO(Gr)/ITO/PET manifests itself in a sharp change of the electrical resistance of the composite film from a low-conducting state to a relatively high-conducting state when applying a bias to Al-ITO electrodes of ˜0.1-0.3 V ( E ˜ 3-5 × 104 V/cm), which is below the threshold switching voltages for similar composites. The mechanism of resistance switching, which is associated with the processes of capture and accumulation of charge carriers by Gr (GO) particles introduced into the matrices of the high-molecular-weight (PVK) and relatively low-molecular-weight (PFD) polymers, was discussed.

  17. ANAEROBIC BIODEGRADATION OF A BIODEGRADABLE MATERIAL UNDER ANAEROBIC - THERMOPHILIC DIGESTION

    Directory of Open Access Journals (Sweden)

    RICARDO CAMACHO-MUÑOZ

    2014-12-01

    Full Text Available This paper dertermined the anaerobic biodegradation of a polymer obtained by extrusion process of native cassava starch, polylactic acid and polycaprolactone. Initially a thermophilic - methanogenic inoculum was prepared from urban solid waste. The gas final methane concentration and medium’s pH reached values of 59,6% and 7,89 respectively. The assay assembly was carried out according ASTM D5511 standard. The biodegradation percent of used materials after 15 day of digestion were: 77,49%, 61,27%, 0,31% for cellulose, sample and polyethylene respectively. Due cellulose showed biodegradation levels higher than 70% it’s deduced that the inoculum conditions were appropriate. A biodegradation level of 61,27%, 59,35% of methane concentration in sample’s evolved gas and a medium’s finale pH of 7,71 in sample’s vessels, reveal the extruded polymer´s capacity to be anaerobically degraded under thermophilic- high solid concentration conditions.

  18. Nanoparticles Decorated on Resin Particles and Their Flame Retardancy Behavior for Polymer Composites

    Directory of Open Access Journals (Sweden)

    Nour F. Attia

    2017-01-01

    Full Text Available New nanocomposites have been developed by doping of amberlite IR120 resin with spherical TiO2 nanoparticles in the presence of maleate diphosphate. Polystyrene composites of resin, maleate diphosphate, and resin-maleate diphosphate were prepared individually. This is in addition to preparation of polymer nanocomposites of polystyrene-resin doped TiO2 nanoparticles-maleate diphosphate. The flame retardancy and thermal stability properties of these developed polymer composites were evaluated. The inclusion of resin and resin doped nanoparticles improved the fire retardant behavior of polystyrene composites and enhanced their thermal stability. Synergistic behavior between flame retardant, resin, and nanoparticles was detected. The rate of burning of the polymer nanocomposites was recorded as 10.7 mm/min achieving 77% reduction compared to pure polystyrene (46.5 mm/min. The peak heat release rate (PHRR of the new polymer composites has reduced achieving 46% reduction compared to blank polymer. The morphology and